Head-mounted physiological signal monitoring system, devices and methods

ABSTRACT

Eyewear apparatus includes dry electrophysiological electrodes and, optionally, other physiological and/or environmental sensors to measure signals such as EOG and ECG from the head of a subject. Methods of use of such apparatus to provide fitness, health, or other measured or derived, estimated, or predicted metrics are also disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. provisional patent applicationNo. 61/940,902, filed Feb. 18, 2014.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to monitoring apparatuses worn by subjectand methods of using the apparatuses to physiological signals from thesubject. The present invention further relates to physiologic monitoringsystems that monitor physiological signals and process the signals inorder to provide various forms of feedback to the user or anotherperson. The present invention further relates to the monitoring andprocessing of physiological signals from a subject to providemeasurements, metrics, information, data, messages, or warnings to theuser based on the monitored physiological signals and related to thesubject's overall health, physical performance, concentration oralertness state, and the like.

2. Technical Background

Presently, there no commercially or otherwise available systems foraccurately, consistently, efficaciously and conveniently monitoring manyphysiological signals from a subject while the subject is performingphysical activity, particularly robust physical activity includingstrenuous exercise. In order to obtain physiological signals under harshor strenuous physical conditions, systems either require a large degreeof preparation, attachment, and securing of sensors to the subject'sbody, or they suffer from disjointed, inaccurate, or noisy signals beingobtained, and thus requiring large degrees of signal processing. In thegrowing market of physical activity for health, sport, competition,training, and the like, there are no products that are able toaccurately obtain strong, clear physiological signals and provide alarge series of data and information based on those signals, while stillproviding the convenience of a simple wearable that can be donned anddoffed as easily as a piece of clothing or a fashion accessory.

It is therefore an object of the present invention to provide systems,devices and methods for acquiring signals from the human body,particularly from a subject's head, using external or surface sensorsrequiring little or no preparation, such as abrading the skin, surgicalimplantation or attachment, adhesives or electrolytic fluids or gelsapplied directly to the skin to aid in signal conduction, or the like.It is a further object of the present invention to allow for such easysignal acquisition of any and all biopotential physiological signals,including, but not limited to electrocardiogram (ECG), electromyogram(EMG), electrooculogram (EOG), electroencephalogram (EEG), partialpressure of oxygen and or carbon dioxide, blood oxygenation, bloodpressure, body conductance, body resistance, galvanic skin response,body potential sensors, temperature (both body and ambient), and thelike, as well as environmental signals relating to the conditionssurrounding the subject's body including motion signals (e.g., fromaccelerometers, gyroscopes). It is especially an object of the presentinvention to provide apparatus which can cleanly acquire both EOG andECG signals from the head of the subject and to use these signals inboth a user interface navigation and also in deriving fitness metricsand reporting those metrics to the subject or others.

It is still further an object of the present invention to provide thesystems, devices and methods in a portable manner. Portability refers tothe preferred ability for the subject to easily carry or wear thesystems or devices, or for such to be readily attached to the subject,his or her clothing or other accessories, or otherwise easily donned andworn/transported/used during strenuous physical activity. Portabilityalso further requires the systems and devices of the present inventionto preferably include a contained power system, data storage andprocessing components, and the ability to transmit or otherwisetelemeter signals from the systems or devices to separate electroniccomponents, potentially over great distances, such as to remotelylocated servers or devices.

It is still further an object of the present invention to provide thesystems, devices and methods in a manner that requires reduced oreliminated power recharging requirements, through the provision ofenergy harvesting components and steps which can generate part or all ofthe needed operational power from environmental or bodily energysources.

SUMMARY OF THE INVENTION

Because the head is far from the sources of electrophysiologicalactivities sought to be measured, e.g., ECG, it is often overlooked as apoint of collection for such signals. However, the inventors havediscovered that the head actually provides a superior signal collectionsite because of (1) the absence of large muscle groups on the head,which are sources of EMG-type electrophysiological noise; (2) the headprovides a variety of unique natural anchor points for sensors that arenot uncomfortable, including in the ears, around the ears, on the bridgeof the nose, and around the circumference of the head, which in turnhelps to reduce motion artifact noise; and (3) the head lends itself toa number of common wearables that can be outfitted with sensors andcomfortably donned and doffed with minimal effort, inconvenience, orsocial stigma. These insights, in combination with the inventors'innovations in dry electrophysiological sensors, have yielded thevarious embodiments of the present invention.

The present invention relates to head-mounted monitoring apparatusesworn by a subject and methods of using the apparatuses to acquire,process, and/or transmit physiological signals from the subject. Thepresent invention further relates to physiologic monitoring systems thatmonitor physiological signals and process the signals in order toprovide various forms of feedback to the subject or another person. Thepresent invention further relates to the monitoring and processing ofphysiological signals from a subject to provide measurements, metrics,information, data, messages, or warnings to the subject based on themonitored physiological signals and related to the subject's overallhealth, physical performance, and the like.

The systems, devices, and methods of the present invention are designedfor use in operations of many varieties. Preferably, the system may beused, or adapted for use, with any head-mounted wearable, includinghats, helmets, eyewear, headbands, earphones, earbuds, or the like. Invarious embodiments the system collects one or more of (1) physiologicalsignals, (2) ambient/environmental signals, and (3) system signals totrack the physiological conditions, metrics and performance of thesubject. Ambient, environmental, and system data may include, but is notlimited to, pressures, temperatures, g-force, altitude, depth,geographical position, and the like. Physiological data such as thesubject's ventilation, fractional concentration of expired oxygen(FEO₂), fractional concentration of expired carbon dioxide (FECO₂),breath-by-breath volume (BV), breath frequency (BF), electrocardiogram(ECG), electroencephalogram (EEG), electrooculogram (EOG), heart rate,skin temperature (including using sensors that collect temperature datafrom multiple skin sites for algorithmic combination of this data toproduce more accurate skin temperature readings), galvanic skinresponse, and blood oxygen saturation (SpO₂) are among the many types ofdata, profiles and metrics that can be acquired alone or in combinationby the various embodiments of the present invention.

Various embodiments of this system are differentiated from traditionalsystems such as, for example, other physiological monitoring systems,particularly heart rate sensors, which rely on inaccurate ECG signalscorrupted by large amounts of noise, artifacts, and variation due to theconditions under which they are used, or others which utilize opticalsensors to read physiological signals from the subject's inner ear. Thepresent invention, contrary to these other systems, acquires stronger,cleaner signals from the subject's body, including ECG signals. Theinvention is able to do so through the use of novel platforms makingadvantageous use of superior body anchor points as well as novel sensortypes, configurations and arrangements; processing combinations ofacquired signals in novel ways to achieve higher-quality data streamsfor analysis; and enhanced features that promote greater comfort,wearability, and usability, which in turn promote more consistent andlonger-term use and thus provide more data and more useful data fromwhich new metrics may be derived. Various embodiments may furtherinclude various platforms for the sensors, such sensors includingtemperature sensors, heat flux sensors, respiration sensors, pressuresensors, physiological electrodes such as ECG, EMG, EOG, and EEG, apulse oximeter, body conductance sensors, body resistance sensors,accelerometers, gyroscopes, body potential sensors, blood pressuresensors, impedance sensors, microphones, body and blood chemistrysensors, galvanic skin sensor and the like, which can be incorporatedfor example into or on caps, glasses or eyewear, sweatbands, headphones,in-ear headphones or ear buds, hats, helmets, and the like. The sensorsof the present invention are able to effectively record signals throughor among areas of the subject body that other sensors cannot, such as onhairy portions of the subject, like the scalp, or sweaty portions,without preparation of the skin (abrading, removal of the hair, etc.).The sensors of the present invention are fit and able to acquire heartrate signals and heart rate variability. The sensors can be tethered byphysical electrical connection or linked wirelessly. The wireless linkcan be through radio frequency, optical link, acoustics and the like.The sensor signals are transmitted through an appropriate link to anelectronic data acquisition or controller or other subsystem that mightin certain embodiments contain either a small on-board processor and/orother electronic components for not only receiving the sensor(s) signal,but also for possibly filtering, digitizing, converting, calculating andthe like of the signal and data into information related to thesubject's physiological condition and in certain embodiments using thatinformation or data to control the delivery of gases, medication, and/orother physical stimulation to the subject. Preferably, the dataacquisition or controller systems, as well as power and transmissionsystems are contained in or on the device or system itself, such asembedded into a pair of eyeglasses or sunglasses, rather than requiringa separate processing unit. The device or system may additionally pairwith other sensor systems attached to the subject or worn by thesubject, for example an arm or torso sensor or an electronic device suchas a digital watch or smart watch, or cellular phone or smart phone, andwhere the invention fuses data from the sensors on the various devicesto provide a more complete and robust set of data as well asrecommendations and/or warnings.

The monitoring apparatus is preferably a small, wearable systemcontaining at least one sensor for detecting and measuring particularconditions of the subject. The apparatus may include one or more of thewearables listed in this application, including but not limited toearphones (including earbuds and headphones), headgear (including hats,helmets, caps, headbands, and masks), eyewear (including eyeglasses,sunglasses, and eyeglasses frames), watches, phones, wristbands, chestbands, arm bands, ankle bands, shoes, clipped-on devices, and hand-helddevices. Preferably, if sensors are implemented across multiple devices,each device is either wired to one or more other devices or the devicesare independently equipped with processors and electronic components fortwo-way wireless transmission of data and instructions, by radio orotherwise, to the various other components as required for datacollection and analysis. Preferably, the sensors make use of the naturalpressure provided by the wearables to hold the sensors securely in placeat natural anchor points on the body. Most preferably, those points areinside the ear and on the temples.

In one embodiment, the invention is an in-ear apparatus for acquiringphysiological signals comprising at least one earbud, the earbud havingat least one soundspeaker and at least one dry electrophysiologicalelectrode, the dry electrode comprising a plurality of low aspect ratioprotruding surface features. Preferably, the surface features have anaspect ratio of less than 1.5. Preferably, the surface features areshaped and arranged as an array of bumps. Also preferably, the earbudfurther comprises at least one other sensor for pressure, temperature,g-force, altitude, galvanic skin response, blood oxygenation, movement,ambient sound, or the speech sound of the user. Preferably, this in-earembodiment uses an infrared (IR) tympanic temperature sensor to aid inproducing energy expenditure models and/or kinematic models. Furtherpreferably, the earbud further comprises a rechargeable battery. Furtherpreferably, the earbud further comprises an electronic radio componentcapable of wireless two-way communication with at least one otherdevice. Further preferably, the dry electrode is formed by a first stepof forming an electrode shape including surface features by injectionmolding, casting or depositing a material into a mold, followed by asecond step of coating at least a portion of the electrode shape with aconductive or semi-conductive film. Alternatively, the dry electrode isformed by coating, deposition, or impregnation of a conductive materialonto or into a pliant material that has been molded or etched to havethe surface features. In such case, preferably, the conductive materialis silver/silver chloride and the pliant material is a polymer,elastomer, foam, or rubber. Further preferably, the at least one earbudis adapted to be mechanically anchored entirely within the ear, withoutexternal support. Alternately, the at least one earbud is adapted to beanchored with support of a hook adapted to be fitted around the ear, andpreferably at least one other physiological or environmental sensor ispositioned on the hook. Further preferably, the at least one earbudfurther comprises an ambient microphone adapted to measure ambient soundsignals, a computer processor adapted to process the ambient soundsignals so as to generate corresponding noise cancelling sound signalsprovided through the at least one soundspeaker, and a user interfaceadapted to permit the subject to be provided with a non-ambient soundsubstantially free of ambient sound, a transparent ambient sound free ofnon-ambient sound, or any continuous mix between the two, through the atleast one soundspeaker.

In another embodiment, the invention is a method of collecting ECGsignals of a subject comprising inserting into the subject's ear anin-ear apparatus for acquiring physiological signals comprising at leastone earbud, the earbud having at least one soundspeaker and at least onedry electrode, the dry electrode comprising a plurality of low aspectratio protruding surface features; measuring with the dry electrode anelectrophysiological signal; amplifying and filtering theelectrophysiological signal to produce an ECG signal; and transmittingor storing the ECG signal for collection. Preferably, the ECG signalsare further processed to determine heart rate. Further preferably, theECG signals are further processed to determine one or more of heart ratevariability, respiration rate as derived from the ECG modulation and/orrespiratory sinus arrhythmia or a combination of the two. Furtherpreferably, at least one other metric is derived based at least in parton the ECG signals and at least in part on one other measuredphysiological or environmental parameter. Also preferably, the heartrate metric, heart rate variability metric, and/or the at least oneother derived metric are reported to the subject and/or form the basisof a notice or warning delivered to the subject by a automatic outputselected from the group consisting of a visual display, an audiblealarm, speech, a mild electrical shock, or an ambient or localizedtemperature change, or a change in the lighting permitted to enter theeyes of the subject.

In yet another embodiment, the invention is a method of providing healthinformation to a subject comprising inserting into the subject's ear anin-ear apparatus for acquiring physiological signals comprising at leastone earbud, the earbud having at least one soundspeaker, at least onedry electrode, and at least one other physiological sensor of adifferent type than electrophysiological, the dry electrode comprising aplurality of low aspect ratio protruding surface features; measuringwith the dry electrode an electrophysiological signal; substantiallysimultaneously, measuring with the at least one other physiologicalsensor a second signal indicative of a physiological parameter; andderiving a physiological metric using at least in part both theelectrophysiological signal and the second signal, wherein the metric isindicative of metabolism, heat loss, calories expended, stress,alertness, concentration, or sleep stage. Optionally, the method furthercomprises the step of delivering an alert or warning to the subjectbased at least in part on the derived physiological metric through oneor more of a visual display, an audible signal, or a change in ambientor localized temperature or light. Also optionally, the method furthercomprises the step of delivering an alert or warning to a person remotefrom the subject via wireless communication; this step may be doneeither before or after detecting that the alert or warning was notheeded by the subject.

In still another embodiment, the invention is a headgear apparatus foracquiring electrophysiological signals comprising a hat or helmetcomprising elastic or contoured foam portions adapted to fit snugly to,and place light pressure on, the head of a subject, and a plurality ofdry electrophysiological electrodes along the elastic or contoured foamportions, the dry electrodes each comprising a plurality of low aspectratio protruding surface features. Preferably, the surface features havean aspect ratio of less than 1.5. Preferably, the surface features areshaped and arranged as an array of bumps. Also preferably, the headgearapparatus further comprises at least one other sensor for pressure,temperature, g-force, altitude, galvanic skin response, bloodoxygenation, movement, ambient sound, or the speech sound of the user.Further preferably, the headgear apparatus further comprises arechargeable battery. Further preferably, the headgear apparatus furthercomprises an electronic radio component capable of wireless two-waycommunication with at least one other device. Further preferably, thedry electrodes are formed by a first step of forming an electrode shapeincluding surface features by injection molding, casting or depositing amaterial into a mold, followed by a second step of coating at least aportion of the electrode shape with a conductive or semi-conductivefilm. Alternatively, the dry electrodes are formed by coating,deposition, or impregnation of a conductive material onto or into apliant material that has been molded or etched to have the surfacefeatures. In such case, preferably, the conductive material issilver/silver chloride and the pliant material is a polymer, elastomer,foam, or rubber.

In still yet another embodiment, the invention is a method of collectingECG signals of a subject comprising placing on the subject's head aheadgear apparatus for acquiring electrophysiological signals, theheadgear apparatus consisting of a hat or helmet comprising elastic orcontoured foam portions adapted to fit snugly to, and place lightpressure on, the head of a subject, and a plurality of dry electrodesalong the elastic or contoured foam portions, the dry electrodes eachcomprising a plurality of low aspect ratio protruding surface features;measuring with the dry electrodes electrophysiological signals;amplifying and filtering the electrophysiological signals to produce ECGsignals; and transmitting or storing the ECG signals for collection.Preferably, the ECG signals are further processed to determine heartrate. Further preferably the ECG signals are further processed todetermine heart rate variability. Further preferably, at least one othermetric is derived based at least in part on the ECG signals and at leastin part on one other measured physiological or environmental parameter.Also preferably, the heart rate metric, heart rate variability metric,and/or the at least one other derived metric are reported to the subjectand/or form the basis of a notice or warning delivered to the subject bya output selected from the group consisting of a visual display, anaudible alarm, speech, a mild electrical shock, or an ambient orlocalized temperature change, or a change in the lighting permitted toenter the eyes of the subject.

In even still another embodiment, the invention is a method of providinghealth information to a subject comprising placing on the subject's heada headgear apparatus for acquiring electrophysiological signals a hat orhelmet comprising elastic or contoured foam portions adapted to fitsnugly to, and place light pressure on, the head of a subject, aplurality of dry electrodes along the elastic or contoured foamportions, and at least one other physiological sensor of a differenttype than electrophysiological, the dry electrodes each comprising aplurality of low aspect ratio protruding surface features; measuringwith the dry electrodes electrophysiological signals; substantiallysimultaneously, measuring with the at least one other physiologicalsensor a non-electrophysiological signal indicative of a physiologicalparameter; deriving at least one physiological metric using at least inpart both the electrophysiological signal and thenon-electrophysiological signal, wherein the metric is indicative ofmetabolism, heat loss, calories expended, stress, alertness,concentration, or sleep stage. Preferably, the method includes thefurther step of determining, with a computer processor, when the atleast one derived metric has exceeded a threshold or has exhibited apredefined or learned pattern; and automatically providing a stimulus tothe subject via a display, alarm, vibrator, buzzer, or stimuluselectrode either integrated into the eyeglasses apparatus or integratedinto a separate device adapted to be kept on the person of the subjectand in communication with the eyeglasses apparatus through either awired or wireless link.

In even yet another embodiment, the invention is a hat for acquiringelectrophysiological signals comprising contoured foam portions adaptedto fit snugly to the head of a subject, and to place light pressure onthe head at various points; a plurality of dry electrodes along theelastic portion at the points of light pressure, the dry electrodes eachcomprising a plurality of low aspect ratio protruding surface features;and one or more electronic components for recording or transmittingsignals measured by the dry electrodes wherein the pressure provided bythe foam portions is sufficient to maintain good electrical contactbetween each of the electrodes and the skin of the subject.

In still a further embodiment, the invention is a headband or sweatbandfor acquiring electrophysiological signals comprising an elasticportion, adapted and shaped to fit snugly to the head of a subject, andto place light pressure on the head at various points; a plurality ofdry electrodes along the elastic portion at the points of lightpressure, the dry electrodes each comprising a plurality of low aspectratio protruding surface features; and one or more electronic componentsfor recording or transmitting signals measured by the dry electrodeswherein the pressure provided by the elastic portion is sufficient tomaintain good electrical contact between each of the electrodes and theskin of the subject.

In yet a further embodiment, the invention is a skull cap, swim cap, ortight-fitting dew-rag for acquiring electrophysiological signalscomprising an elastic portion, adapted and shaped to fit snugly to thehead of a subject, and to place light pressure on the head at variouspoints; a plurality of dry electrodes along the elastic portion at thepoints of light pressure, the dry electrodes each comprising a pluralityof low aspect ratio protruding surface features; and one or moreelectronic components for recording or transmitting signals measured bythe dry electrodes wherein the pressure provided by the elastic portionis sufficient to maintain good electrical contact between each of theelectrodes and the skin of the subject.

In even a further embodiment, the invention is a helmet for acquiringelectrophysiological signals comprising an elastic portion, adapted andshaped to fit snugly to the head of a subject, and to place lightpressure on the head at various points; a plurality of dry electrodesalong the elastic portion at the points of light pressure, the dryelectrodes each comprising a plurality of low aspect ratio protrudingsurface features; and one or more electronic components for recording ortransmitting signals measured by the dry electrodes wherein the pressureprovided by the elastic portion is sufficient to maintain goodelectrical contact between each of the electrodes and the skin of thesubject.

In now an additional embodiment, the invention is an eyewear apparatusfor acquiring electrophysiological signals comprising eyeglasses frameshaving temple stems and having a plurality of dry electrodes along thestems, the dry electrodes each comprising a plurality of low aspectratio protruding surface features. The eyewear apparatus may beeyeglasses, sunglasses, eyeglass frames without lenses, or a visualdisplay device anchored by stems to the ears and/or nose. Preferably,the electrode surface features have an aspect ratio of less than 1.5.Preferably, the surface features are shaped and arranged as an array ofbumps. Further preferably, each stem has at least one dry electrodeadapted for placement nearer to the eyes for detecting an EOG signal andat least one dry electrode adapted for placement above the ears fordetecting an ECG signal. Also preferably, the eyewear apparatus furthercomprises at least one other sensor for pressure, temperature, g-force,altitude, galvanic skin response, blood oxygenation, movement, ambientsound, or the speech sound of the user. Further preferably, the eyewearapparatus further comprises a rechargeable battery. Further preferably,the eyewear apparatus further comprises an electronic radio componentcapable of wireless two-way communication with at least one otherdevice. Further preferably, the dry electrodes are formed by a firststep of forming an electrode shape including surface features byinjection molding, casting or depositing a material into a mold,followed by a second step of coating at least a portion of the electrodeshape with a conductive or semi-conductive film. Alternatively, the dryelectrodes are formed by coating, deposition, or impregnation of aconductive material onto or into a pliant material that has been moldedor etched to have the surface features. In such case, preferably, theconductive material is silver/silver chloride and the pliant material isa polymer, elastomer, foam, or rubber. Further preferably, the eyewearapparatus further comprises a user interface that is navigable and/oroperable with the detected EOG signal(s), as well as blink artifactsdetected in the EOG signal(s). Further preferably, the eyewear includesa visual display. Further preferably, the lenses of the eyewear areelectronically darkenable, especially upon detection of a physiological,environmental, or combined physiological-environmental condition.

Optionally, the eyewear apparatus further comprises one or two earbudsconnected to the stems of the glasses by wires and adapted to bemechanically anchored entirely within the ear, without external support,the earbud(s) having soundspeaker(s) and at least one of earbuds havingan additional electrophysiological sensor. Further preferably, theeyewear apparatus further comprises an ambient microphone adapted tomeasure ambient sound signals, a computer processor adapted to processthe ambient sound signals so as to generate corresponding noisecancelling sound signals provided through the soundspeaker(s), and auser interface adapted to permit the subject to be provided with anon-ambient sound substantially free of ambient sound, a transparentambient sound free of non-ambient sound, or any continuous mix betweenthe two, through the at least one soundspeaker.

In still an additional embodiment, the present invention is a method ofcollecting ECG signals of a subject comprising placing on the subject'shead an eyewear apparatus for acquiring physiological signals comprisingeyeglasses frames having temple stems and having a plurality of dryelectrodes along the stems, the dry electrodes each comprising aplurality of low aspect ratio protruding surface features; measuringwith the dry electrodes electrophysiological signals; amplifying andfiltering the electrophysiological signals to produce ECG signals; andtransmitting or storing the ECG signals for collection. Preferably, themethod also includes the step of collecting EOG signals from the subjectwith dry electrodes placed along the stems nearer to the eyes of thesubject. Further preferably, the method includes the step of navigatingand operating a user interface using the collected EOG signals. Inrelated embodiments, preferably, EOG signals and blink ratedeterminations are used as a measure of the subject's level ofengagement, general attention, or attentional fixation on a givenobject-of-attention.

In yet another embodiment, the present invention is a method ofproviding health information to a subject comprising placing on thesubject's head an eyewear apparatus for acquiring physiological signalscomprising eyeglasses frames having temple stems, having a plurality ofdry electrodes along the stems, and having at least one otherphysiological sensor of a different type than electrophysiological, thedry electrodes each comprising a plurality of low aspect ratioprotruding surface features; measuring with the dry electrodeselectrophysiological signals; substantially simultaneously, measuringwith the at least one other physiological sensor anon-electrophysiological signal indicative of a physiological parameter;deriving at least one physiological metric using at least in part boththe electrophysiological signal and the non-electrophysiological signal,wherein the metric is indicative of metabolism, heat loss, caloriesexpended, stress, alertness, concentration, or sleep stage. Preferablythis method, further comprises the steps of determining, with a computerprocessor, when the at least one derived metric has exceeded a thresholdor has exhibited a predefined or learned pattern; and automaticallyproviding a stimulus to the subject via a display, alarm, vibrator,buzzer, or stimulus electrode either integrated into the eyewearapparatus or integrated into a separate device adapted to be kept on theperson of the subject and in communication with the eyeglasses apparatusthrough either a wired or wireless link.

Additional features and advantages of the invention will be set forth inthe detailed description which follows, and in part will be readilyapparent to those skilled in the art from that description or recognizedby practicing the invention as described herein, including the detaileddescription which follows, the claims, as well as the appended drawings.

It is to be understood that both the foregoing general description andthe following detailed description are merely exemplary of theinvention, and are intended to provide an overview or framework forunderstanding the nature and character of the invention as it isclaimed. The accompanying drawings are included to provide a furtherunderstanding of the invention, and are incorporated in and constitute apart of this specification. The drawings illustrate various embodimentsof the invention, and together with the description serve to explain theprinciples and operation of the invention. They are not, however,intended to be limiting or to illustrate all envisioned embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C. An earbud embodiment of the present invention.

FIG. 2. Communication between the earbud embodiment and other device(s).

FIG. 3. Communication between the earbud embodiment and a healthmonitor.

FIG. 4. A wireless earbud embodiment used as a driving alert or arousalsystem.

FIGS. 5A-5G. Eyewear apparatus embodiment(s) of the present invention.

FIG. 6. A hearing aid embodiment of the present invention.

FIGS. 7A-7B. A custom-molded earbud embodiment of the present invention.

FIG. 8. A sports helmet embodiment of the present invention.

FIG. 9. A sports helmet embodiment of the present invention.

FIG. 10. A swim cap or similar tight-fitting skull cap embodiment of thepresent invention.

FIG. 11. A ballcap embodiment of the present invention.

FIG. 12. A headband or sweat band embodiment of the present invention.

FIG. 13. Flow chart showing various methods of various embodiments ofthe present invention.

FIG. 14. Flow chart showing various methods of the present invention.

FIGS. 15A-C Illustration of several embodiments of a dry electrode ofthe present invention from various perspectives, including: (A) bottomview; (B) top view; and (C) cross-section with conductive coating and/orionic compound.

DESCRIPTION OF WEARABLES, SENSORS, ACTUATORS, AND COMPUTED METRICS USEDIN THE PREFERRED EMBODIMENTS

The present invention provides physiological data acquisition,processing, transmission, and/or information provision/warningapparatuses worn by a subject and methods of using the apparatuses toacquire, process, and/or transmit physiological signals from thesubject. Some embodiments of the present invention further providephysiologic monitoring systems that monitor physiological signals andprocess the signals in order to provide various forms of feedback to thesubject or another person. Some embodiments of the present inventionfurther provide monitoring and processing of physiological signals froma subject to provide measurements, metrics, information, data, messages,or warnings to the user based on the monitored physiological signals andrelated to the subject's overall health, physical performance, and thelike.

Various embodiments of the present invention include sensors andcomponents for storage and/or transmission of signals integrated into awearable that preferably anchors the sensors to the body with little ormore preferably no preparation of the skin surface and preferably withno sensor attachment or setup procedure beyond the typical donning ofthe wearable itself. Wearables used in embodiments of the presentinvention include caps, glasses or eyewear, sweatbands, headphones,in-ear headphones or ear buds, hats, helmets, and the like. Thesewearables provide for both enforcement of proper placement andappropriate pressure on the body surface of the various sensors,including dry electrodes, used to monitor physiological parameters ofthe subject and/or collect environmental information, such as ambientaudio data or ambient temperature data. The wearable(s) of the variousembodiments may also be used to protect one or more electricalcomponents and allow for the connection of various sensors to theelectrical components within or on the wearable(s), the electricalcomponents being for amplification, processing, storage, and/ortransmission of measured sensor signals, and/or for providing feedbackor stimulus to the subject, which may include audio, video, tactile,electrical, or other sensory stimulus. The wearable will preferably haveelectrical connections or connectors incorporated or embedded into thestructure of the wearable, so that various sensors are connected to theelectrical components. The wearable can be constructed from any suitablematerial and using any method known in the art; including, but notlimited to, various types of textiles and fabrics, various types ofwood, various types of plastics, various types of polymers, varioustypes of resin, various types of ceramics, various types of metals, andvarious types of composite materials.

Wearables

In many embodiments the present invention consists of one or more of thefollowing wearables having one or more of the following sensors coupledto a processor and one or more of the following actuators.

Headgear. Headgear is defined generally as anything worn about the head,but excluding articles which are applied only to the face. Certaineyewear that wraps around the head, such as traditional glasses andgoggles, but excluding pince-nez and monocles, are to be consideredheadgear. Headgear further includes hats, helmets, and masks that fitabout the head.

Eyewear. Eyewear includes any worn apparatus fitted to the head or facethrough which the eyes peer. Eyeglasses, sunglasses, goggles, monocles,pince-nez, and certain masks may be considered eyewear. Implements heldup to the face for a short period in order to peer through them, such astraditional binoculars, telescopes, spyglasses, and the like are notconsidered eyewear for the purposes of this application.

Headphones. Headphones consist of a pair of earphones that completelycover or largely cover the ears, and without fitting inside of the ears,joined by a band placed over the head.

Earbuds. Earbuds consist of smaller earphones that fit inside the ears.For the purposes of this application, the term “earbud” excludes deviceswhich enclose the ear or which substantially cover the outer surface ofthe ear; ear buds include only those devices which fit snugly into theouter ear canal and are there anchored. Thus, the terms “headphones” and“earbuds” should be considered to be mutually exclusive. Headphones andearbuds have both structural and functional differences that areimportant to this application, as headphones are not anchored to theears in the same ways that earbuds are and can be more easily jostledand disturbed during vigorous activity such as jogging.

Hats. Hats are headgear that fit entirely about the head and cover thehead. Hats include ballcaps and knit caps.

Helmets. Helmets are headgear that fit entirely about the head and aresufficiently rigid to protect the head from impacts. Helmets frequentlyhave inner padding that helps to fit them to the contours of the headand further helps to absorb impacts.

Masks. Masks are headgear that generally cover all or part of the faceand function either to disguise or to protect or both. Masks have someprovision to see through them in at least some conditions. A welder'smask is an example of a mask that provides protection and the ability tosee through in very bright (but not dark) conditions.

Visors. Visors are headgear that fit substantially (but not alwaysentirely) about the head and include a front brim that acts as aneyeshade, but a visor does not totally cover the head on the top. In thecontext of helmets, however, the word “visor” as used in thisapplication does not refer to a piece of headgear, but rather to a glassor glass-like piece fitting in the helmet permitting visibility throughthe front of the helmet while providing protection.

Gloves. Gloves may be used to provide haptic feedback to the subject aswell as to sense hand motions, postures, gestures, and/or pressures asforms of input to the device of the present invention. Preferably, thesensors and/or actuators of the gloves of the present invention arewirelessly coupled to the processor and/or sensors and/or actuators ofsome other device, including one or more of the other wearablesdescribed herein. Gloves are especially advantageous as input mechanismsand output actuators where the hands of the subject are occupied with acontrol task, as with controlling a vehicle (airplane, helicopter,automobile, bicycle, motorcycle, etc.) or other equipment. For example,a bicycle rider wearing bicycle gloves may control the other systems ordevices of the present invention by squeezing certain fingers or partsof the palm, and without letting go of the bicycle handlebars.

Wristwatches. Watches, and particularly smart watches, may be fittedwith the sensors of the present invention may serve as the primarydevice of the present invention or more preferably may supplement orsupport an eyewear, earphone, headwear or other device by providingadditional physiological or environmental sensors and/or by providing auser interface. In such cases the wristwatch advantageously communicateswith the other device(s) of the present invention using a wirelessprotocol such as Bluetooth.

Sensors

The physiological and environmental sensors of the present inventioninclude, in various embodiments, the types described in detail below.

Dry electrodes. Many embodiments of the present invention may utilizedry physiological electrodes to acquire many physiological signals fromthe subject, and in some instances to provide actuated feedback to thesubject based on measurements and calculations provided by the system.The term “dry electrode” as used in this application does not refermerely to any dry apparatus or device used as an electrode, such as adry metal plate or other dry metallic surface; rather, the dryelectrodes of the present invention are designed to provide theperformance associated with typical gelled, or “wet,”electrophysiological electrodes. Examples of dry electrodes may be foundin U.S. Pat. Nos. 6,785,569, 7,032,301, 7,032,302, 7,286,864, 7,489,959,and 7,881,764, which are incorporated by reference. Dry electrodesprovide the advantage that there is no gel to dry out, no skin to abradeor clean, and that the electrode can be applied in hairy areas such asthe scalp. Specifically, such advantages of many of the dry electrodeembodiments incorporated from the above patents are enabled by thesurface features described in said patents, which provide increasedsupport and stability when the electrode is placed on the subject,increased ability be placed in traditionally unusual parts of the body,such as on the head or scalp where hair prevents typical electrodes fromobtaining physiological signals, and which substantially eliminate theneed to prepare the subject's skin or use electrolytic fluids or gels toefficaciously acquire signals. The use of dry physiological electrodesalso provides uncommon reusability and the possibility forlong-term/long-duration wear and/or monitoring. Thus, an earbud, hat,helmet, or eyewear having such dry electrodes can be reused virtuallylimitlessly and may be worn comfortably for hours or days at a timewithout the necessity for electrode replacement and without appreciableloss in the quality of collected signals. Additionally, if electrodesare used as the sensor(s), preferably at least two electrodes areused—one signal electrode and one reference electrode—and if furtherphysiological signal channels are desired, the number of electrodesrequired will depend on whether separate reference electrodes or asingle reference electrode is used, as would be understood by a personskilled in the art.

If electrodes are used to pick up electrophysiological signals, theseelectrodes, for example when measuring cardiac signals usingelectrocardiography (ECG), may be placed at specific points on thesubject's body. ECG is used to measure the rate and regularity ofheartbeats as well as the size and position of the chambers, any damageto the heart, and in diagnosing sleeping disorders. As the heartundergoes depolarization and repolarization, electrical currents spreadthroughout the body because the body acts as a volume conductor. Theelectrical currents generated by the heart are commonly measured by anarray of preferably not more than 10 electrodes, placed on the bodysurface. In traditional arrangements, electrodes may be placed on eacharm and leg, and six electrodes may be placed at defined locations onthe chest. The specific location of each electrode on a subject's bodyin such traditional arrangements is well known to those skilled in theart and varies amongst individual and different types of subjects.Although a full ECG test usually involves ten electrodes, only two arerequired for many other applications such as sleep studies, heart ratemonitoring during exercise, and many others. These may be placed on thesubject's left-hand ribcage, under the armpit and on the right-handshoulder, near the clavicle bone, or in other convenient locations oneither side of the subject's body. However, for purposes of the presentinvention, preferably, sensors, including electrodes as sensors, areplaced on various points on the subject's head in order to acquire ECGand other physiological signals. As few as two electrodes may be used,at least one for acquiring the biopotential signal and at least one as aground electrode, but any number could be used limited only by placementlocations on the subject's head, or by the desired number of channelsrequired or desired to be acquired. In some embodiments of the presentinvention, preferably, ECG is acquired using dry ECG electrodes placedin or near the subject's ears; the electrodes may be mounted on orintegrated into such platform wearables as earbuds, headphones,sweatbands, hats, caps, helmets, eyewear, and the like.

The dry physiological electrode sensors of the present invention can beused in a variety of applications including for measuring variousbiopotentials including but not limited to ECG, electroencephalogram(EEG), electromyogram (EMG), and electrooculogram (EOG), and for takingother physiological measurements, such as galvanic skin response andtemperature, that can be determined from the skin or subcutaneous layersof the subject. The sensors can further be used for any otherapplication wherein ionic potentials are measured. The ionic potentialscan be acquired and transmitted via the dry electrodes in similarmanners as biopotentials using a “wet” electrode, and thus variousmeasurements and calculations can be obtained and/or performed fromthose potentials. Further still, the dry electrode may be used forpoint-to-point measurements between electrodes. Examples of these othertypes of applications may include, but are not limited to, bloodcomposition measurements such as glucose or alcohol concentration, orelectrical impedance measurements such as electrode impedance, skinimpedance, or impedance of fluids in the body.

The dry electrodes of the present invention are applied to a subject,which can be an animal or human body having skin comprising an epidermiscomprising a stratum corneum layer and lower layers of the epidermis,and a dermis. The dry electrodes of the present invention furtherpreferably comprise at least one surface feature on the lower surface ofthe device, the surface that comes into contact with the subject's skin.The surface feature(s) increases the surface contact with the skin andtransforms a portion of the ionic current into an electric voltage thatcan be transmitted through these individual surface feature(s). Thesurface features further enhance the stability of the device when placedon the subject's skin, and serve to decrease electrical impedance, thusfacilitating transmission of a stronger, higher quality signal.Preferably, the surface feature(s) minimize(s) or eliminate(s) movementof the dry electrode with respect to the subject's skin so as tominimize or eliminate certain types of signal distortion associated withsuch motion (i.e., motion artifact).

The dry electrode of the present invention has an upper and a lowersurface. The lower surface of the dry electrode is preferably thesurface that comes into contact with the subject's skin, when the dryelectrode is placed onto the subject. The lower surface may take on manyshapes or arrangements, and may further include a number of surfacefeatures for displacing, cracking, or perturbing the stratum corneum orouter layer of the epidermis, for accessing the lower layers of theepidermis, thus decreasing the electrical resistance of the electricalpathway from the lower layers to the dry electrode, and/or for theachieving the other benefits mentioned above and below in thisspecification. These surface features may take one of many formsincluding, but not limited to, bumps, spikes, cones, ridges, columns,penetrators, anchors, epidermal stops and combinations thereof. Thedescribed surface features, in general, protrude from the various shapedsubstrates described above. Preferably, the surface features arelow-profile cones, rounded bumps, or rounded bumps that are justslightly pointed at the tips (i.e., with inverted dimples). Preferably,there is at least one structure or surface feature protruding from thedry electrode's lower surface; more preferably, there are a multiplicityof such surface features arranged in an array, either evenly-spaced orin a spacing that otherwise meets the needs of the particularapplication (e.g., denser central spacing with gradually more diffusespacing toward the periphery, or vice-versa). One of the importantsecondary functions of the configuration of surface features is todisplace or move the hair, dead skin cells and/or detritus so that thesurface features can better collect the electrical biopotentialsgenerated by the body. The sizes of the surface features are alsoimportant: when surface features are too small, they cannot sufficientlycompress the supper layer of skin, while when surface features are toolarge, they tend to be uncomfortable.

The dry electrode of the present invention further comprises an uppersurface. In some embodiments of the present invention, the upper surfacecan have various types of connectors formed or attached on the top orupper surface of the dry electrode. The connector can simply be a commonbutton type connection in order to connect to standard terminals forvarious devices or can be shaped to provide for unique connectingfeatures in order to require special terminals to be created for themonitoring device. These connectors may be integrated into or with theupper surface or may be a separate component attached to the uppersurface. Preferably, however, rather than having a connector, which mayunnecessarily and uncomfortably protrude, the upper surface of the dryelectrode is directly electrically connected to other components foramplifying, filtering, processing, recording, and/or transmittingacquired signals without the use of a connector element; morepreferably, the dry electrodes of the present invention and theirelectrical connections are integrated into the structure of the wearable(earbud, hat, helmet) as much as possible so as to provide maximumcomfort, simplicity, and reusability; such integration impliesmanufacturing that eliminate connectors and prefers permanentconnections between dry electrode elements and electrical componentelements.

Various embodiments of the present invention comprise a separateencouragement ring for the dry electrode(s). The encouragement ring hasan opening into which a dry electrode, or recording portion of the dryelectrode, can be placed, and which allows the encouragement ring tosurround and hold, preferably firmly, the recording portion. Thisencouragement ring provides stability to the dry electrode such thatwhen the device is placed on a subject's skin, the ring encourages thedevice to become seated in contact with the subject's skin and tominimize movement of the device. This encouragement ring effectivelyhelps to further anchor the dry electrode to the subject's skin byproviding a biasing force that tends to drive or hold the device downonto the subject's skin and thus seating the device, and moreimportantly the surface feature(s), securely in contact with thesubject's skin. This helps to increase signal quality and efficacy whileminimizing artifacts, particularly movement artifacts, in thephysiological signal being acquired. Additionally, the encouragementring provides increased surface area to the upper surface of the dryelectrode which allows the device to be combined with an adhesive collaror some wearable device, system or garment to be applied to thesubject's skin in a more stable and secure fashion. The encouragementring may be of any shape (such as circular or rectangular) toaccommodate the wearable garment or adhesive that may be used to applythe device to a subject.

Other embodiments of the present invention may not include a separateencouragement ring, but rather have a lip which may curve up from thelower surface of the dry electrode acting like an encouragement ring,and which surrounds and provides an edge for a stamped or molded sheetmetal or plastic piece. This lip provides the same function and utilityas the separate encouragement ring described above, but is integratedinto the dry electrode when manufactured, and thus is not separate.

Additionally or alternatively to the above-described encouragement ring,the wearables of the present invention preferably employ compressibleand springy padding or cushioning which assists in gently pressing theelectrode(s) or other sensor(s) against the skin of the subject so as tomaximize skin-sensor contact and minimize motion artifact-causingskin-sensor movement. The electrodes may also (or alternatively) bepressed against the skin by the natural action or fit of the wearable orsome component thereof. For example, the temple stems and hinges ofeyewear may provide gentle pressure against a subject's head forelectrodes or other sensors mounted on or integrated into the stems, orthe elastic band of a ball cap or natural compression of a knit cap mayprovide similar inward pressure for the advantageous mounting of sensorsinside those wearables.

Many embodiments of the dry electrode of the present invention,particularly those where the dry electrode is constructed of anon-conductive material, comprise a conductive coating and/or ioniccompound which helps to create an electrical pathway for signals to betransferred from the subject to the monitoring equipment, and tominimize electrical impedance of the device. Conversely, someembodiments may not require or utilize a conductive coating or ioniccompound at all, most notably those embodiments wherein the electrode isconstructed of a conductive metal. Alternatively, some embodiments maybe coated in a less expensive metallized conductive coating (typically apolymer or plastic device), and receive a conductive coating and/orionic compound on only a portion of the device, such as just the surfacefeature(s). Typically, this coating is a silver/silver chloride(Ag/AgCl) coating, but it may be of any conductive or ionic compoundknown to those in the art presently, or later developed for such use.Alternatively, Ag/AgCl inks or other conductive inks, such as those soldby DuPont (DuPont 5874), Ercon, and the like may be used, as well as anywith the appropriate electrical and/or ionic properties, and which canbe compounded and used for such applications as described herein.

The Ag/AgCl coating utilized may help to ensure the dry electrodes aresubstantially nonpolarizable. Nonpolarizable electrodes are those inwhich current passes freely across the interface between the electrodeand the skin, and thus require no energy to make the transition. A dryelectrode utilizing Ag/AgCl is typically governed by two separatereactions: 1) oxidation of silver atoms on the electrode surface tosilver ions in the material at the interface, and 2) the combination ofsilver ions (Ag⁺) with chlorine ions (Cl⁻) at the material at theinterface. In this case, the material at the interface containing thechlorine ions may include biological fluids of the subject. Thus thisreaction may further be enabled by the concentration of chlorine ions inbiological fluids. Thus, when the dry electrode is placed in contactwith the subject's skin, the Ag/AgCl coating on the device may firstoxidize creating silver ions, and then those silver ions combine withfree chlorine ions contained in the material at the interface includingthe biological fluids of the subject. This interface creates asubstantially nonpolarized connection that allows for the free flow ofbiopotential signals from the subject into the dry electrode with aminimized impedance. Preferably, the amount of Ag/AgCl used to createthese reactions and minimize electrical impedance of the device isminimized in thickness, weight, and/or surface area in order to keepmanufacturing costs low.

Preferably, the conductive coating and/or ionic compound covers no moreof the dry electrode than necessary, and is minimized to reduce cost ofmanufacturing the device. In monolithic embodiments, the conductivecoating and/or ionic compound typically and traditionally can cover theentire lower surface of the dry electrode and at least some portion ofthe upper surface connecting the lower surface to the connector of theupper surface of the device, creating a continuous pathway of theconductive coating and/or ionic compound from the lower surface to theconnector (or point of connection, in embodiments without connectors).Some embodiments provide the conductive coating and/or ionic compound ona portion of the lower surface of the device, for example only coatingthe center most portion of the lower surface, or coating just the tipsor ends of the surface feature(s) which are in contact with thesubject's skin when the device is applied to the subject. In suchembodiments, preferably less than 90% of the lower surface has theconductive coating and/or ionic compound. More preferably less than 80%of the lower surface has the conductive coating and/or ionic compound.Still more preferably less than 70% of the lower surface has theconductive coating and/or ionic compound. Even more preferably less than60% of the lower surface has the conductive coating and/or ioniccompound. Even still more preferably less than 50% of the lower surfacehas the conductive coating and/or ionic compound. More preferably still,less than 40% of the lower surface has the conductive coating and/orionic compound. Even still more preferably less than 30% of the lowersurface has the conductive coating and/or ionic compound. Still yet morepreferably, less than 20% of the lower surface has the conductivecoating and/or ionic compound. Even still more preferably, less than 10%of the lower surface has the conductive coating and/or ionic compound.

In other monolithic embodiments, the coating is not applied to the lowersurface of the dry electrode based the inner radius of the lower surfacecovered, but rather such coating is further minimized by applicationonly to the surface features located on the lower surface. Theseembodiments differ from the above described embodiments because thecoating here is only applied to the surface features and enough of theinterstitial space between the surface features to create a web-likeconductive network connecting each of the surface features to eachother. In other words, the coating is not applied to the entire selectedinner radius of the dry electrode, thus coating the entire inside ofthat radius, but is rather selectively and specifically applied to thesurface features and a network connecting those surface featurestogether. This allows the amount of coating required to be minimizedeven further, and thus reduce costs even further. In such embodiments,preferably less than 30% of the lower surface has the conductive coatingand/or ionic compound. More preferably less than 25% of the lowersurface has the conductive coating and/or ionic compound. Even morepreferably less than 20% of the lower surface has the conductive coatingand/or ionic compound. Still more preferably less than 15% of the lowersurface has the conductive coating and/or ionic compound. Even stillmore preferably less than 10% of the lower surface has the conductivecoating and/or ionic compound. In such embodiments, the percentage ofthe lower surface that is covered in the conductive coating and/or ioniccompound is easily managed by decreasing the amount of connectingpathways between surface features and/or decreasing the width and depthof the coating constituting those pathways.

Another way to measure the amount of conductive coating and/or ioniccompound used, in order to minimize that amount, is by the amount ofsurface area that is actually covered. In regards to actual surface areacoated, preferably, the surface area coated in conductive coating and/orionic compound is less than 6 cm² for any one dry electrode. Morepreferably, the surface area coated in conductive coating and/or ioniccompound is less than 5.5 cm². Still more preferably, the surface areacoated in conductive coating and/or ionic compound is less than 5 cm².Yet more preferably, the surface area coated in conductive coatingand/or ionic compound is less than 4.5 cm². Even more preferably, thesurface area coated in conductive coating and/or ionic compound is lessthan 4 cm². More preferably still, the surface area coated in conductivecoating and/or ionic compound is less than 3.5 cm². Yet more preferably,the surface area coated in conductive coating and/or ionic compound isless than 3 cm². Still yet more preferably, the surface area coated inconductive coating and/or ionic compound is less than 2.5 cm². Evenstill more preferably, the surface area coated in conductive coatingand/or ionic compound is less than 2 cm². Even still yet morepreferably, the surface area coated in conductive coating and/or ioniccompound is less than 1.5 cm². Still even more preferably, the surfacearea coated in conductive coating and/or ionic compound is less than 1cm². Even still yet more preferably, the surface area coated inconductive coating and/or ionic compound is less than 0.75 cm². Stilleven more preferably yet, the surface area coated in conductive coatingand/or ionic compound is less than 0.5 cm² for any one dry electrode.

In both varieties of embodiments of the above described monolithic dryelectrodes, the minimized area of conductive coating and/or ioniccompound on the lower surface of the device must comprise a continuouspathway of the coating from that coated area to and around the edge ofthe encouragement lip to the upper surface of the device, and to theconnector located on said upper surface. Such continuous pathway allowsthe biopotential signals to be transmitted from the subject to themonitoring equipment in spite of the use of a non-conductive dryelectrode body and a preferably minimized amount of conductive coatingand/or ionic compound. This continuous pathway may be created byproviding a strip-like path of the conductive coating and/or ioniccompound from the portion of the lower surface out from the center ofthe lower surface towards the edge of the device, around the edge of thedevice thus connecting the lower surface to the upper surface, and thento the center of the upper surface of the device and to the connector.In some embodiments, multiple such strips are provided to ensure astrong, secure electrical pathway from the surface features to theconnector and to the monitoring equipment, for example in case onepathway becomes damaged, rubs away, or is otherwise broken. However,preferably, only a single pathway of connective coating is provided, andis applied in a manner and with properties so as to ensure a continuouselectrical connection and pathway.

The dry electrode can be formed from a variety of materials andprocesses known to those skilled in the art. The substrate from whichthe surface features are formed or to which they are added can, by wayof example but not limitation, be made from the following: a conductivemetal sheet, where such conductive metals include, but are not limitedto, stainless steel, nickel, copper, aluminum, and the like; asemi-conductive material, including, for example, silicon and dopedsilicon wafers; ceramics, including, for example, oxides; polymers,including, for example, electrically conductive polymers such aspolyimides; and other varieties of plastics. Preferably, allnon-conductive substrates are coated, such as with Ag/AgCl, or doped tomake the substrate semi-conductive or conductive. There are in generalfour processes by which embodiments of the dry electrodes of the presentinvention are preferably manufactured: injection molding, casting ordepositing; replication; micro-machining; or stamping or pressing from asheet of metal, polymer sheet or polymer powders.

It is understood that the dry electrodes of the present invention mayhave a combination of the various surface features described throughoutthis application. Various features of the present invention aredescribed within this patent application. It is understood that thepresent invention can be considered to embody many of these features invarious combinations without departing from the spirit of the presentinvention. A small number of examples of the present invention aredescribed in the following embodiments. Various features and functionsof the present invention are discussed in greater detail in U.S. Pat.Nos. 6,782,283, 6,785,569, 7,032,301, 7,286,864, 7,489,959, and8,201,330, and U.S. patent application Ser. No. 13/826,185, all of whichdisclosures are incorporated by reference into the present application.

As described earlier, the dry electrode of the present inventioncomprises an upper and a lower surface. The lower surface can take manyforms. For instance, the lower surface can be flat, concave, convex, orsome other unique shape. The dry electrode can be substantially flat onits lower surface. Various embodiments of the present invention couldinclude changes in the dry electrode's lower surface. Whether the lowersurface is perpendicular to the dry electrode's vertical axis or slopeddepends on the application. The dry electrode can also be substantiallyconcave on its lower surface. An example is where the lower surface isoutwardly curved like a portion of the inner surface of a large sphere.The dry electrode can also have a convex shape on its lower surface. Anexample is where the lower surface curves or bulges outward, like aportion of the exterior surface of a large sphere. The lower surface ofthe dry electrode is not limited to one of the aforementioned shapes,and may take on a number of other unique shapes or some combination ofthe shapes listed above. Preferably, the dry electrode is molded orshaped to match the shape of the wearable into which it is incorporated;thus, the lower surface might be convex for an earbud and slightlyconcave for a hat, helmet, or sweatband.

As discussed above, the lower surface of the dry electrode of thepresent invention may further include a number of surface features fordisplacing, cracking, or perturbing the stratum corneum or outer layerof the epidermis and accessing the lower layers of the epidermis. Suchdisplacing, cracking, or perturbing of the skin may include the surfacefeatures physically penetrating the stratum corneum and accessing andphysically contacting the lower layers of the skin. However, it may bepreferable for the surface features to merely perturb, stretch, or openthe stratum corneum by cracking or displacing it without actuallyphysically penetrating it, in order to provide a lower electricalresistance pathway from the lower layers of the skin to the dryelectrode. Penetrating surface features can take many shapes includingbut not limited to pyramidal, needle-like, triangular, or any othershape that can be tapered to a point or tip. Where the surface featuresare penetrating, preferably, the size and shape of the penetrator issuch that the penetrator(s) will not break or bend during normal use,will limit the depth the penetrator enters the skin under typicalapplication conditions, and/or will anchor the device to prevent motionartifacts or any substantial movement. Such penetrating surface featuresare explained in detail in U.S. Pat. No. 6,785,569 to Schmidt et al.,which is incorporated by reference.

A ridge as a surface feature of a dry electrode is preferably a long,narrow structure or elevation. The ridge(s) can have a variety of crosssections over a length. Examples of these cross sections include, butare not limited to, a square, rectangle or trapezoid, a pointed surfacelike that of a triangle, a domed surface like that of an arch or arc, across section with a concave surface between to ridge lines forming thetwo ridge lines, some other unique cross-section or the like. The crosssection of the ridge extends for a length. The length of the ridge ispreferably substantially longer than the height or width of thecross-section of the ridge. The surface of the ridge away from thesubstrate, when applied to the skin surface, depresses, but does notneed to penetrate the skin but anchors the device in place to preventmotion artifacts, to displace hair, dead skin cells and/or detritus, toincrease the surface area of the device in contact with the skin, and tobe capable, in part, of transmitting an electric potential which can bemeasured from the surface of the skin through the ridge.

A column is another type of structure or elevation that can be used as asurface feature of the dry electrode of the present invention. A columncan have a variety of cross sections over a length. Examples of thesecross sections include, but are not limited to, a square, rectangle ortrapezoid, a pointed surface like that of a triangle, a domed surfacelike that of an arch or arc, a cross section with a concave surfacebetween two points (wherein the distance from the base to either pointis greatest height of the column for the cross-section), some otherunique cross-section or the like. The cross section of the column like aridge extends for a length. However, the width of the column ispreferably in proportion to the height of the cross-section of thecolumn, and more preferably shorter than the height of the column. Thesurface of the column away from the substrate, when applied to the skinsurface, depresses, and does not easily penetrate the skin but anchorsthe device in place to prevent motion artifacts, to displace hair, deadskin cells and/or detritus, to increase the surface area of the devicein contact with the skin, and to be capable, in part, of transmitting anelectric potential which can be measured from the skin through theridge.

A penetrator is another surface feature that can be used in the dryelectrode of the present invention. The penetrator is sized and shapedfor displacing, cracking, or perturbing the stratum corneum or outerlayer of the epidermis, and accessing the lower layers of the epidermis.The penetrator can take many shapes, including, but not limited to,pyramidal, needle-like, triangular, or any other shape that can betapered to a point or tip. The surface of the penetrator away from thesubstrate, when applied to the skin surface, readily penetrates theskin, preferably anchors the device in place to prevent motion artifactsor any substantial movement, increases the surface area of the device incontact with the skin and lower layers of the epidermis, and is capable,in part, of transmitting an electric potential which can be measuredfrom the skin and lower layers of the epidermis through the penetrator.

The epidermal stop, which can be used in the present invention, is astructure or elevation. Epidermal stops are structures of a particularheight with respect to the height of the penetrator(s) or other surfacefeatures so as to prevent the penetrator(s) or other surface featuressuch as columns and ridges from penetrating into the dermis of the skinor unduly distorting the surface of the skin, respectively, where theymight cause discomfort to the subject. Epidermal stops may also beincorporated into a penetrator, ridge, column or like surface feature orcan be a separate surface feature. The epidermal stops may, however,have any shape known to those skilled in the art that would effectivelyprevent the penetrator(s) from entering the dermis of the skin, or frombeing applied to deeply. The epidermal stops are preferably applied inan array among the penetrators, therefore further minimizing inadvertentdeep penetration or over penetration by the penetrator(s) or minimizingsignificant distortion of the skin by other surface structures. If theepidermal stop is a separate surface feature or incorporated intoanother structure, preferably, the epidermal stop in combination with atleast one other surface feature or two structures with incorporatedepidermal stops create a detritus trough.

A detritus trough is the area interposed between adjacent surfacestructures or features. These troughs, when provided or naturallyoccurring in the design, allow for a more accurate placement of thesurface features by allowing for displacement of the hair and otherdetritus on the skin in these troughs. Preferably, the detritus troughsare sufficient in number and size to allow for placement of the deviceon skin with a significant amount of hair such as for example the scalpor the chest of a male subject. Detritus troughs are created to maximizethe area available for optimal device to skin contact, by improving theprobability that hair and other detritus will enter the troughs and notpreventing the surface features from either coming in contact with theskin or penetrating the skin. Thus detritus troughs may be parallel toone another, perpendicular to one another, or in any other orientationmade to improve the contact of the device with the skin of the subject.

An anchor, which can be used in the present invention, is a structure orelevation that stabilizes the physiological device against a subject'sskin. This stabilization further preferably prevents motion artifacts inthe electrophysiological signal from the device, or any substantialmovement. While the anchor can also be any of the structures describedabove, the anchor may also serve no other purpose except to stabilize orreduce movement of the device on the subject's skin. The anchor(s) canhave a variety of cross sections over a length as described above forthe various surface structures.

The ridges, columns and penetrators also increase the amount of surfacearea of the skin in contact with the dry electrode, which is applied.This allows for greater pick up of (or stronger) signals from the skin'ssurface, and further allows for the dry electrode to be better anchoredto the subject's skin resulting in less artifacts to the signal throughmovement and the like. The electric voltage from these surface featuresis measured using conventional measuring devices.

As discussed earlier, the dry electrode further comprises an uppersurface, which is the surface that faces away from the subject when thedry electrode is applied to the subject. In some embodiments, the uppersurface may comprise some variety of connector used to connect the dryelectrode to monitoring equipment, and to complete an electrical pathwayfrom the lower layers of the subject's skin to said monitoringequipment. The connector may be of any variety commonly known to thoseof skill in the art currently, or later developed. Examples of suchconnectors include, but are not limited to, snap connectors, buttonconnectors, tension or compression fittings, and the like.

As discussed previously, an independent, separate encouragement ring, towhich an independent electrode component can be attached, may beprovided. The independent, separate encouragement ring comprises anopening in its center with a diameter equal to that of an independent,separate recording portion, preferably comprising surface features. Theopening allows the recording portion to be placed inside of theencouragement ring's opening, and allows the encouragement ring tosurround and hold the recording portion. The independent recordingportion may attach to the opening of the encouragement ring by threads,a locking system, thermal compression, or like techniques. When theseparate encouragement ring and recording portions are combinedtogether, they form a single dry electrode as described above,comprising an upper and a lower surface. The separate encouragement ringpreferably curves up, away from the subject's skin when applied, suchthat, when viewed from the lower surface, the dry electrode has a convexshape. This encouragement ring provides stability to the dry electrodesuch that when the device is placed on a subject's skin, the ringencourages the device to become seated in contact with the subject'sskin and to minimize movement of the device. This helps to increasesignal quality and efficacy while minimizing artifacts in thephysiological signal being acquired. Additionally, the encouragementring provides increased surface area to the upper surface of the dryelectrode which allows the device to be combined with an adhesive collaror some wearable or garment to be applied to the subject's skin in amore stable and secure fashion.

The use of a separate encouragement ring provides advantages such asallowing for the dry electrode to be manufactured using differentmaterials for its different portions (i.e., separate encouragement ringand recording portions). The use of different materials for thedifferent portions of the electrode provides benefits both in themanufacture and use. With respect to manufacturing, the separateencouragement ring may be constructed of a less expensive material, suchas various low cost of plastics known to those skilled in the art. Thus,the entire separate encouragement ring, which constitutes a significantportion of the entire assembled recording device, may be made from amaterial, and by a process that reduces manufacturing costs, andtherefore helps reduce overall cost of the electrode. Further, theseparate encouragement ring allows for the amount of conductive coatingand/or ionic compound required to be minimized by creating an electricalpathway between the two separate portions, rather than all the way outand around the edge of the encouragement ring. These cost-cuttingfeatures particularly provide an advantage over existing dry electrodeswhich are known to those skilled in the art to be expensive to producedue to the use of expensive conductive materials, or the need tocompletely cover the electrode in an expensive conductive coating and/orionic compound such as Ag/AgCl.

In addition to reducing costs of the device, using a separateencouragement ring allows the encouragement ring and the recordingportion to be constructed of materials that have different properties toprovide different features to the device. For example, the recordingportion is preferably constructed of a material that has electricalconductive properties and electrical impedance properties that areconducive to transmitting biopotential signals from the subject to themonitoring equipment, or alternatively (or additionally) may be anon-conductive material that is coated in a conductive layer such asAg/AgCl to reduce the impedance, provide an electrical pathway, andprovide a redox reaction promoting the flow of ions and thus allowingfor better signal transmission. However, the encouragement ring beingconstructed of a different material allows the ring to provideadditional characteristics, features, or properties to the device whenassembled. The separate encouragement ring may be constructed of amaterial with a particular stiffness which helps anchor the device moresecurely to the subject's skin. Particular levels of flexibility mayalso be achieved with the encouragement ring, allowing the device to besituated on a curvier or less regularly-shaped part of the body whilestill providing the function of situating the recording portion insecure contact with the subject's skin. The encouragement ring materialcan be chosen based on any number of such desired features orcharacteristics, and still provide the reduction in cost whilemaintaining the secure fit of the electrode to the body. The end resultof providing a separate encouragement ring constructed of a differentmaterial is that the function of the encouragement ring, to provideanchoring of the device to the subject's skin, can be optimized tobetter situate or apply the device in different locations of the body.Different materials yield different properties in the encouragementring, and thus provide the applicable biasing forces causing the deviceto anchor to the skin, differently in different locations. Someencouragement rings may be adapted to affix the device to hairy regionsof the body, or to curvier regions. Having separate encouragement ringsallows the device to be applied in many different locations andfashions, while still providing the required biasing forces to thesubject's skin to drive the device down into the skin, and more securelyanchor the device thereto. In some embodiments this ensures a higherquality signal is transmitted from the subject to the monitoringequipment, and further minimizes artifacts and noise within the signal.The separate encouragement ring may be attached to the electrode orrecording portion by any means currently known to those in the art orlater developed, including, but not limited to, threads, compression,clips or other mechanical fixture methods, adhesives, and the like.

Other embodiments of the present invention do not include a separateencouragement ring. In such embodiments, the dry electrode is made froma single piece of material, and in some embodiments it preferablycomprises a lip extending radially outward and curving upward away fromthe lower surface of the recording device, surrounding and providing anedge for a stamped or molded sheet metal or plastic piece. This lipprovides the same function and utility as the separate encouragementring described above, but is part of a unitary construction of the dryelectrode, rather than being a separate piece that is later attached toa separate recording portion. The lip comprises the edge or near-edgeportion of the dry electrode, and the lip is herein preferably definedas the portion where the lower surface of the dry electrode begins tocurve upward to the edge or near edge of the dry electrode.

The distance of the curved lip portion is herein defined as the distanceof curvature of the lip. The same distance of curvature definitionapplies to the curved portion of the separate encouragement ring inembodiments comprising a separate encouragement ring. The curvature ofthe lip or encouragement ring may be wholly contained in the lip orencouragement ring portion, or may begin in the lower surface of therecording portion of the device itself. That is, the lower surfaceitself need not be entirely flat, but may gradually curve up into thelip or encouragement ring. Many embodiments are envisioned with bothconstructions: either with a flat area between the lower surface wherethe surface features are located and where the lip or encouragement ringbegins, or where the lower surface itself begins to curve up and meetthe curvature of the lip or encouragement ring to form an essentiallysmooth curve. In all embodiments having such a design, preferably, thedistance of curvature of the lip or separate encouragement ring isgreater than 0.2 cm. More preferably, the distance of curvature of thelip or separate encouragement ring is greater than 0.25 cm. Still morepreferably, the distance of curvature of the lip or separateencouragement ring is greater than 0.3 cm. Yet more preferably, thedistance of curvature of the lip or separate encouragement ring isgreater than 0.4 cm. Even more preferably, the distance of curvature ofthe lip or separate encouragement ring is greater than 0.45 cm. Stillyet more preferably, the distance of curvature of the lip or separateencouragement ring is greater than 0.5 cm. Still even more preferablythe distance of curvature of the lip or separate encouragement ring isgreater than 0.6 cm. Yet still more preferably, the distance ofcurvature of the lip or separate encouragement ring is greater than 0.75cm. Yet even more preferably, the distance of curvature of the lip orseparate encouragement ring is greater than 1.0 cm. Even yet morepreferably, the distance of curvature of the lip or separateencouragement ring is greater than 1.5 cm. Most preferably, the distanceof curvature of the lip or separate encouragement ring is greater than2.0 cm.

The lip, by its very nature, has a radius of curvature which defines therate at which the lip curves upward from the lower surface of the dryelectrode. It is to be understood that the entire lip or encouragementring does not need to have the same or constant radius of curvaturealong the entire distance of curvature. In other words, it is importantto note that the radius of curvature may change along the length of thedistance of curvature. Preferably, the radius of curvature of the lip orencouragement ring over substantially all of the distance of curvatureis greater than 0.5 cm. More preferably, the radius of curvature of thelip or encouragement ring over substantially all of the distance ofcurvature is greater than 0.75 cm. Still more preferably, the radius ofcurvature of the lip or encouragement ring over substantially all of thedistance of curvature is greater than 1.0 cm. Yet more preferably, theradius of curvature of the lip or encouragement ring over substantiallyall of the distance of curvature is greater than 1.125 cm. Even morepreferably, the radius of curvature of the lip or encouragement ringover substantially all of the distance of curvature is greater than 1.25cm. More preferably still, the radius of curvature of the lip orencouragement ring over substantially all of the distance of curvatureis greater than 1.5 cm. Yet more preferably still, the radius ofcurvature of the lip or encouragement ring over substantially all of thedistance of curvature is greater than 1.75 cm. Still even morepreferably, the radius of curvature of the lip or encouragement ringover substantially all of the distance of curvature is greater than 2.0cm. Even still more preferably, the radius of curvature of the lip orencouragement ring over substantially all of the distance of curvatureis greater than 2.5 cm.

It should be noted that not all embodiments will utilize encouragementrings or curved lip portions in the dry electrode; in many embodiments,such as ear bud embodiments, the dry electrode will be integrated intothe wearable without such features.

Body temperature sensors. Many embodiments of the present inventionfurther include sensors for measuring the subject's body temperature.Because body temperature affects the rate of chemical reactions criticalto normal body operation and healthy survival, the body'sthermoregulation mechanisms attempt to keep the subject at optimumoperating temperature, 37° C. (98.6° F.) on average in humans, withvariation among individuals and in accordance with seasonal, hormonaland menstrual cycles and circadian rhythms—with about 0.5° C. (0.9° F.)variance between daily high and low points. Increased body temperatureis indicative of strenuous physical activity, and body temperaturechange—whether severely increased or severely decreased—is alsosymptomatic of illness or other dangerous conditions such ashypothermia. Eating, drinking, and smoking can all influence bodytemperature, as can sleep disturbances (with temperature dropping duringrest). Thus, monitoring of body temperature can provide useful exerciseand health information, and can alert the subject to take a break fromexercise, to oncoming sickness, to bedtime or waketime, to mealtime orcaloric restriction, to periods of fertility, etc. It is also believedthat an increase in daily body temperature variation can provide anindicator of increased overall physical fitness.

Body temperature may also vary based on measurement methods andparticularly the placement of the measurement sensor. Among healthyadults, typical daytime temperatures are about 37.5° C. (99.5° F.) forrectal, vaginal, or otic measurements; about 36.8° C. (98.2° F.) fororal measurements; and about 36.5° C. (97.7° F.) for axillarymeasurements under the armpit. Although different sensor placements mayyield different measurements, measurements from different points tend tobe correlated, thus the temperature at one point can be estimated orpredicted with measurement from another point; however, axillary, otic,and other skin-based temperatures may sometimes correlate poorly withcore body temperature, and skin-based temperatures are more variablethan other measurement sites as the body uses the skin as a coolingdevice. Resultantly, skin temperatures are more influenced by ambienttemperatures than core temperatures are. Preferably, temperature ismeasured at multiple sites and the acquired measurements arealgorithmically combined using methods such as weighted averages toyield more accurate temperature readings.

For head-worn or head-based systems such as the present invention, thereare several viable options for measuring the subject's body temperature,including orally, otically, from the forehead, or from the superficialtemporal artery. The preferred methods and sensors used to measure bodytemperature vary based on the particular embodiment. For example, a capor hat embodiment may readily use sensors that measure the temperaturefrom the subject's forehead, but an embodiment of headphones would morereadily benefit from a temperature sensor in the ear (tympanic) or overthe superficial temporal artery. The superficial temporal artery is amajor artery located in the head that arises from the external carotidartery when the external carotid bifurcates and separates into thesuperficial temporal artery and the maxillary artery. The superficialcarotid artery exhibits a palpable pulse detectable superior to thezygomatic arch, anterior and superior to the tragus, and is locatedclose to the surface of the skin in most subjects, and thus offers anaccurate, accessible and efficacious source for measuring the subject'sbody temperature, as long as the subject's flow of blood is permanentand regular. Such sensors can be of any variety capable of sensing andmeasuring temperature transcutaneously. Otic and forehead bodytemperature sensors typically use infrared sensors, by, for example,shining an infrared light off the tympanic membrane. Thermistors andthermocouples can in some cases also be used to acquire body temperaturemeasurements.

Galvanic skin response sensors. Galvanic skin response sensors measure asubject's level of excitement, stress, or other such indicators ofpsychological or physiological stimulation or arousal, as a function ofthe increased skin conductance caused by the increase in sweat. Skinconductance is a measure of the electrical conductance of the skin, andis commonly known in the art as one of several names, including galvanicskin response (GSR), electrodermal response (EDR), psychogalvanic reflex(PGR), skin conductance response (SCR) or skin conductance level (SCL).Galvanic skin response typically varies based on the moisture level ofthe subject's skin, such as is caused by sweating. Galvanic skinresponse may measure stimulation or arousal due to the fact that sweatis controlled by the sympathetic nervous system, which is the part ofthe autonomic nervous system that initiates or activates thefight-or-flight response to some stimulus applied to the sympatheticneurons.

Galvanic skin response sensors measure the recorded electricalresistance between two electrodes when a very weak current is steadilypassed between them. The sensors are normally placed a short distanceapart, and the resistance recorded varies in accordance with theemotional state of the subject. Galvanic skin potential (GSP) refers tothe voltage measured between two electrodes without any externallyapplied current, and is measured by connecting the electrodes to avoltage amplifier. Similarly, this voltage varies with the emotionalstate of the subject. Galvanic skin response can be highly sensitive toemotions in some people, though the GSR measurement cannot differentiatebetween what emotions are causing the response. GSR measurements aretypically very small, such as on a microsiemen scale, but an accuratelyand correctly calibrated sensor and signal acquisition device orelectronics can readily ascertain and measure such small values andchanges in the GSR on such a scale. Because the fight-or-flightresponse, activated by the release of noradrenaline and adrenaline, alsoresults in increased heart rate, a correlation between increasedelectrical conductance of the skin (as measured by a GSR sensor) andincreased heart rate (as measured by a heart rate sensor such as an ECGsensor or an IR/optical sensor) can provide an especially good indicatorof excitement/stress.

Pulse oximetry sensors. Another example of the sensors that may be usedin conjunction with the present invention include the use of a pulseoximeter. Pulse oximeters of any type known to those skilled in the artmay be used. Generally, depending on the location of attachment to thesubject's body, pulse oximeters tend to be either transmission or backscatter (reflection) sensors. Transmission sensors operate by generatinga source of light at a known frequency and wavelength, passing saidlight through the subject's body, and measuring the amount of light thatexits the subject's body on the other side. Transmission sensors, andparticularly pulse oximeters, are typically applied fingertips, thenose, or earlobe, due to the thinness of those parts of the body and theease in applying a sensor to both sides thus enabling the transmissionmeasurement. On other areas of the body that do not lend themselves aswell to applying such sensors, and back scatter or reflection sensorsmay be used. Back scatter sensors operate by generating a source oflight at a known frequency and wavelength, and then measuring the amountof light that bounces or reflects back to the measurement sensor whichis on the same side as the light generator. These sensors tend to beless accurate than transmission sensors due to the loss of light as itscatters once it enters the subject's body; 100% reflection is generallyunachievable. In spite of the generally decreased accuracy, thesesensors, particularly in pulse oximeters, are useful for application tothe subject's ear to which would be uncomfortable and difficult to applya transmission sensor. More specifically, with regard to the preferredsensor, the pulse oximeter can measure the oxygenation of the subject'sblood by producing a source of light originating from the oximeter attwo wavelengths (such as, in one embodiment, 650 nm and 805 nm). Thelight is partly absorbed by hemoglobin, by amounts which differdepending on whether it is saturated or desaturated with oxygen. Bycalculating the absorption at the two wavelengths the proportion ofhemoglobin which is oxygenated can be estimated. Some embodiments, wherethe optional pulse oximeter is attached to or incorporated into ahelmet, may be referred to as helmet-mounted pulse oximeter (HMPO)embodiments. In some embodiments, a pulse oximeter may be placed on asubject's fingertip. In other embodiments, a pulse oximeter may beplaced directly on a subject's earlobe or forehead. In yet otherembodiments, a pulse oximeter may be incorporated into a mask, helmet,or some other wearable, and then placed on the subject's forehead orearlobe when the mask, helmet or wearable is donned. In still yet otherembodiments, a pulse oximeter may be attached in the subject's ear cup.In yet other embodiments, a pulse oximeter may be incorporated into amask, helmet, or some other wearable, and is then placed in thesubject's ear cup. In even other embodiments, a pulse oximeter may beapplied to the bridge of the subject's nose, and is preferablyincorporated into a mask, helmet, or other wearable.

Near infrared sensors. Near-infrared (NIR) sensors may be included inmany embodiments of the present invention. An example of an applicationfor near-infrared measurements is for pulse oximetry and measurement ofblood oxygen concentration. The primary application of NIRS to the humanbody uses the fact that the transmission and absorption of NIR light inhuman body tissues contains information about hemoglobin concentrationchanges. When a specific area of the brain is activated, the localizedblood volume in that area changes quickly. Optical imaging can measurethe location and activity of specific regions of the brain bycontinuously monitoring blood hemoglobin levels through thedetermination of optical absorption coefficients.

NIRS can be used for non-invasive assessment of brain function throughthe intact skull in human subjects by detecting changes in bloodhemoglobin concentrations associated with neural activity, e.g., inbranches of cognitive psychology as a partial replacement for functionalMagnetic Resonance Imaging (fMRI) techniques. NIRS can be used oninfants, and NIRS is much more portable than fMRI machines, evenwireless instrumentation is available, which enables investigations infreely moving subjects. However, NIRS cannot fully replace fMRI becauseit can only be used to scan cortical tissue, where fMRI can be used tomeasure activation throughout the brain. Special public domainstatistical toolboxes for analysis of stand alone and combined NIRS/MRImeasurement have been developed (NIRS-SPM).

The application in functional mapping of the human cortex is calleddiffuse optical tomography (DOT), near-infrared imaging (NIRI) orfunctional NIRS (fNIR). The term diffuse optical tomography is used forthree-dimensional NIRS. The terms NIRS, NIRI, and DOT are often usedinterchangeably, but they have some distinctions. The most importantdifference between NIRS and DOT/NIRI is that DOT/NIRI is used mainly todetect changes in optical properties of tissue simultaneously frommultiple measurement points and display the results in the form of a mapor image over a specific area, whereas NIRS provides quantitative datain absolute terms on up to a few specific points. The latter is alsoused to investigate other tissues such as, e.g., muscle, breast andtumors. NIRS can be used to quantify blood flow, blood volume, oxygenconsumption, reoxygenation rates and muscle recovery time in muscle.

By employing several wavelengths and time resolved (frequency or timedomain) and/or spatially resolved methods blood flow, volume andabsolute tissue saturation (StO₂ or Tissue Saturation Index (TSI)) canbe quantified. Applications of oximetry by NIRS methods includeneuroscience, ergonomics, rehabilitation, brain computer interface,urology, the detection of illnesses that affect the blood circulation(e.g., peripheral vascular disease), the detection and assessment ofbreast tumors, and the optimization of training in sports medicine.

The use of NIRS in conjunction with a bolus injection of indocyaninegreen (ICG) has been used to measure cerebral blood flow and cerebralmetabolic rate of oxygen consumption. It has also been shown that thecerebral metabolic rate of oxygen (CMRO2) can be calculated withcombined NIRS/MRI measurements.

NIRS is starting to be used in pediatric critical care, to help dealwith cardiac surgery post-op. Indeed, NIRS is able to measure venousoxygen saturation (SVO₂), which is determined by the cardiac output, aswell as other parameters (fraction of inspired oxygen (FiO₂),hemoglobin, oxygen uptake). Therefore, following the NIRS gives criticalcare physicians a notion of the cardiac output. NIRS is liked bypatients, because it is non-invasive, is painless, and uses non-ionizingradiation.

Optical Coherence Tomography (OCT) is another NIR medical imagingtechnique capable of 3D imaging with high resolution on par withlow-power microscopy. Using optical coherence to measure photon pathlength allows OCT to build images of live tissue and clear examinationsof tissue morphology. Due to technique differences OCT is limited toimaging 1-2 mm below tissue surfaces, but despite this limitation OCThas become an established medical imaging technique especially forimaging of the retina and anterior segments of the eye.

GPS sensors. Global positioning system (GPS) sensors may also beincluded on many embodiments of the present invention. GPS sensors areknown in the art to be useful in tracking the subject's location,distance traveled, and speed. GPS measurements can also be combined withaccelerometry measurements or other measurements of pedometry to gauge asubject's pace, defined as the average distance one foot travels fromthe point it leaves the ground until the same foot touches the groundagain. Pace can be computed by dividing distance traveled over number ofpaces (i.e., the number of two-step sequences). Measurements from GPS ordeterminations based on GPS are useful for fitness and healthapplications wherein an athlete or person exercising can track his orher distance covered during exercise, and can be useful in otherapplications, for tracking similar values. For example, an Over the Roadtruck driver may use various embodiments of the present inventionincluding a GPS sensor to monitor the distance traveled on a trip whilemonitoring the various other signals and measurements described herein,thus allowing for tracking of a particular shipment as well as providingmessages or warnings to the driver when it is time to pull over and restto improve the safety of the truck driver and other motorists on theroad. This may be done with maximum efficiency because safe, legal,convenient, or otherwise appropriate places to pull over may bepredefined in the GPS system, thus, a trucker will not be forced to pullover to rest in a place where it is unsafe, illegal, inconvenient, orotherwise inappropriate to do so. The GPS sensors of the presentinvention may additionally, in some optional embodiments, be able toprovide altitude measurements as well, by utilizing a trilaterationtechnique of synchronizing and measuring the distances between thesystem or device and at least four different satellites.

Accelerometers. Accelerometers may be used to measure determine thesubject's body position and orientation, g-forces, and provide otherfunctions such as providing time synchronization with the subject'svehicle (e.g., aircraft). Such accelerometers may be of any type knownto those skilled in the art, including magnitude accelerometers and3-axis accelerometers. Preferably, the accelerometers aremicro-electro-mechanical systems (MEMS) based. Accelerometers are oftenincluded to detect high g-force conditions, angular movements andaccelerations, and the like. The time synchronization feature primarilyallows for post-mission (in military applications) or post-applicationreview of data in which the subject's position and orientation, as wellas g-forces experienced, are compared via time signature to known eventsor occurrences detected by other sensing systems, or other sensors onthe same device. This helps to align data points in order to allow andfacilitate analysis of what circumstances may lead to or cause the onsetof dangerous conditions, episodes or events in order to help develop newpreventative, mitigating, or treatment systems and methods.Accelerometry data can also be used to derive pedometric data becausethe recorded shock of landing on a foot is indicative of a taken step.In combination with GPS data or other data indicative of distancetraveled, this pedometric data can yield stride, a useful metric forwalkers and runners.

Gyroscopes. Another type of sensor included in many embodiments of thepresent invention includes gyroscopes. Gyroscopes are often used tomeasure, detect or otherwise determine orientation of the subject or thesystem or device. Preferably, electronic or MEMS-based gyroscopes areused. The gyroscopes of the present invention are preferably 3-axisgyroscopes, thus requiring only a single gyroscopic device to measurethe angular momentum, and thus orientation, in all three dimensions oraxes rather than using three separate gyroscopes where one measures eachdimension or axis. The preferred characteristics aid in miniaturizationand accuracy of the measurements of the system and devices, while alsoensuring the most comfortable and enjoyable fit and experience for theuser. Inclusion of gyroscopes in particular embodiments of the presentinvention, particularly in conjunction with accelerometers, allows thesystem and devices to detect and measure the subject's movement. Suchmeasurements of movement aid in the tracking of health-related metricsand allow for a more robust and diverse set of data to be collected aswell as derived.

The motion sensors (including accelerometers and gyroscopes) of thepresent invention can also be used in processing and filtering the datafrom other sensors, including electrophysiological and IR sensors, whichtend to be sensitive to motion artifacts, using cancellation methodsknown in the art to assist in the attenuation and removal of motionartifacts from collected data.

Altimeters. Altimeters are yet another type of sensor that may beincluded in various embodiments of the present invention. Altimeters aresensors that are able to detect and measure the altitude of the systemor device, and thus the subject wearing, using or otherwise employingthe system or device. A measure of altitude is particularly importantfor fitness applications to determine elevation climbed and/or descendedduring a workout routine, as when jogging through hilly terrain,mountain climbing, or ascending buildings.

As noted herein, some optional embodiments may provide altitudemeasurements using a GPS sensor as opposed to a separate, dedicatedaltimeter, where the GPS sensor uses a trilateration technique tomeasure the distance between the system or device and at least fourdifferent satellites. Also optionally, and particularly for applicationsin vehicles or aircraft, a radar altimeter or other such altimeters thatrequire a reference signal to be sent out (e.g., phase radio-altimeters)may be used in order to provide more accurate and precise altitudemeasurements where the increased precision is beneficial. However, inmost embodiments a traditional pressure altimeter is the preferred type.Pressure altimeters measure the atmospheric pressure surrounding thesystem, device or subject. Typically, pressure altimeters compare theambient atmospheric pressure to the pressure at sea level, and thus givean altitude measurement that corresponds to a height above sea level. Asis known in the art, the greater the altitude, the lower the pressure,and thus the altimeter measures the pressure and calculates the altitudeaccording to this inverse relationship and in relation to the pressureat sea level. Altimeters, like most sensors, require calibration becausethe pressure measurement is greatly variable and reliant on manyenvironmental factors such as, for example, absolute temperature,gravitational acceleration and molar mass of the air surrounding thesensor. Changes in air pressure directly and significantly affect themeasurement provided by altimeters, and changes in the weather (e.g.,approach of a cold or warm front) can result in large fluctuations inaltitude measurement without actually changing altitude. One simple wayof calibrating the altimeter is to connect to the Internet, preferablythrough a wireless connection, and receiving from a nearby weatherstation the sea level ambient air pressure. The same data may also beinput manually, but automatic calibration is preferred. Pressurealtimeters are one example of a specific type of ambient pressure sensorthat may be included with various embodiments of the present invention,though other pressure sensors may be included as well.Piezoresistor-based barometers such as the STMicroelectronics LSP331AP,as incorporated in smartphones, are known in the art and are accurateenough to distinguish between different floors of a building. Anotherexample of an inexpensive MEMS barometer is the Freescale SemiconductorMPL115A2.

Pressure sensors. Many embodiments of the present invention furtheremploy at least one pressure sensor. Pressure sensors may be includedand used to measure many different pressures relating to physiologicalor environmental attributes of the subject. For example, in someembodiments where the subject is utilizing a breathing system of somevariety (e.g., pilot wearing a flight mask, diver, and the like)pressure sensors may be included inside a breathing mask to measurein-mask pressure. Pressure sensors may also be included in the subject'sgear or clothing, for example a dive suit or a flight vest. Vest or gearor clothing pressure becomes particularly important with regard highaltitude, low pressure environments, such as pilots, aircrew, spacecraftcrew, and the like. Many embodiments of the present invention aredesigned to be used in very low pressure environments, such as thosejust listed. In such environments, pressurized gas is often delivered tothe subject through such a facemask. In order to actually breathe saidgas, the subject often requires clothing or gear (e.g., flight vest) toprovide counterpressure against the lung pressure created by thepressurized gas delivery. Such counterpressure is absolutely necessaryin environments above what is known as the Armstrong Line, which isapproximately located an altitude of 12 miles above sea level (between18,900 to 19,350 meters), and which represents the altitude above whichatmospheric pressure is so low that humans absolutely require apressurized environment to survive. The pressure gradient created by thepressurized environment is what allows the human lungs to perform theirfunction and for breathing to occur. In other words, the requiredpressure gradient, which is the difference between lung pressure andabsolute pressure around the subject, is supplemented or created by theclothing or gear in some embodiments. Thus, pressure sensors in thesubject's gear or clothing in such environments allows the system tomonitor the subject's breathing conditions and detect or predict if thepressure gradient is sufficient to allow healthy breathing.

Other pressure sensors may also be included to measure ambient pressuresurrounding the subject. Preferably, pressure sensors used for measuringmask and/or vest or clothing pressure are gauge pressure sensors. Gaugepressure sensors, as known to those skilled in the art, are those inwhich the pressure of the desired space or area is referenced againstambient pressure, and the differential between the two spaces ismeasured. Thus, in the example of a pilot in flight, the sensor formeasuring either mask pressure or vest pressure is preferably a gaugepressure sensor comprising at least two channels for air intake, oneopen to the pilot's mask or flight vest, and the other channel open tothe ambient, in-cabin pressure surrounding the pilot. The differentialbetween the mask or flight vest pressure and the ambient in-cabinpressure is measured to determine the mask or vest pressure. The same orsimilar sensors might be used to measure mask or clothing/gear pressurefor other subjects as well, firefighters, first-responders, rotorcraftpilots and crew, other fixed wing aircraft crew, or any other subjectutilizing such clothing, equipment or gear.

Still other pressure sensors may also be included. Many embodiments maycomprise at least one pressure sensor for measuring ambient pressureseparately from any user-related pressure. Such ambient pressure sensorsmay be used to separately measure cabin pressure (for aircraft andvehicles), ambient air pressure (for man-mounted systems utilized bysubjects on the ground or in non-pressurized vehicle cabins, or for highaltitude training or exercise purposes), ambient water pressure fordivers, and the like. Typically, such sensors are absolute pressuresensors. Absolute pressure sensors are known to those skilled in the artto measure the differential between the measured atmospheric pressureand a sealed atmospheric channel within the sensor. Preferably, thesealed channel, or internal vacuum reference chamber, in the sensor issubstantially set to about 1 atmosphere (atm), which is equal to about1013.25 millibar (mbar). 1000 mbar is approximately the standard airpressure at sea level. Thus, the measured ambient pressure is comparedagainst the sealed channel's set pressure, and the measured differentialbetween the two is the absolute pressure surrounding the subject. Inmany embodiments, gauge pressure sensors and absolute pressure sensorsmay be used in conjunction with each other to create a more completepressure profile for the user and his or her environment. Such pressuremeasurements can then be used, either alone or in conjunction with themeasurements and recordings of the other sensors described herein, tohelp monitor the subject's status, to help detect and predict the onsetof dangerous conditions, to mitigate or prevent the onset of suchconditions and their symptoms by triggering a warning or alarm to theuser or a third party, or triggering automated or semi-automatedmeasures.

Pressure sensors used with the present invention preferably require lowpower, and are capable of operating accurately and repeatably in extremeconditions (e.g., high pressure, high temperature, low temperature,etc.). The preferred pressure sensors are piezoresistive in nature.Pressure sensors used in the present invention may be of virtually anytype known to those skilled in the art (e.g., Honeywell TRUSTABILITYseries pressure sensors). If such commercially available sensors areused, they are either altered or repackaged in a housing as describedherein to become modular, and readily adaptable for use in the variousbreathing systems and environments for which the present invention isintended to be used. Such housings containing the sensors are then ableto be attached to, combined with, or integrated into breathing systemseither as part of the construction of said system, or as a retrofit ontoan existing system. With regard to the environments in which suchsensors are used, as is known to those skilled in the art, pressuredecreases as altitude increases. Preferably, for ground or airapplications, the pressure sensors used have an effective measurementrange of at least +/−1000 mbar. More preferably, for ground or airapplications, the pressure sensors used have an effective measurementrange of at least +/−900 mbar. Still more preferably, for ground or airapplications, the pressure sensors used have an effective measurementrange of at least +/−800 mbar. Yet more preferably, for ground or airapplications, the pressure sensors used have an effective measurementrange of least +/−700 mbar. Even more preferably, for ground or airapplications, the pressure sensors used have an effective measurementrange of least +/−600 mbar. Still yet more preferably, for ground or airapplications, the pressure sensors used have an effective measurementrange of least +/−500 mbar. Even yet more preferably, for ground or airapplications, the pressure sensors used have an effective measurementrange of least +/−400 mbar. Yet still more preferably, for ground or airapplications, the pressure sensors used have an effective measurementrange of least +/−300 mbar. Even still more preferably, for ground orair applications, the pressure sensors used have an effectivemeasurement range of least +/−200 mbar. Most preferably, for ground orair applications, the pressure sensors used have an effectivemeasurement range of at least +/−100 mbar.

Conversely, for underwater applications, pressure increases as thesubject increases his or her depth, and thus pressure is measureddifferently than for air applications; however, these sensors stilloperate on the same principles. Preferably, for underwater applications,the pressure sensors used have an effective measurement range of least+/−1000 mbar. More preferably, for underwater applications, the pressuresensors used have an effective measurement range of least +/−2000 mbar.Still more preferably, for underwater applications, the pressure sensorsused have an effective measurement range of least +/−4,000 mbar. Yetmore preferably, for underwater applications, the pressure sensors usedhave an effective measurement range of least +/−8,000 mbar. Even morepreferably, for underwater applications, the pressure sensors used havean effective measurement range of least +/−12,000 mbar. Still yet morepreferably, for underwater applications, the pressure sensors used havean effective measurement range of least +/−16,000 mbar. Even yet morepreferably, for underwater applications, the pressure sensors used havean effective measurement range of least +/−20,000 mbar. Yet still morepreferably, for underwater applications, the pressure sensors used havean effective measurement range of least +/−25,000 mbar. Even still morepreferably, for underwater applications, the pressure sensors used havean effective measurement range of least +/−30,000 mbar. Still even morepreferably, for underwater applications, the pressure sensors used havean effective measurement range of least +/−35,000 mbar. Yet even morepreferably, for underwater applications, the pressure sensors used havean effective measurement range of least +/−40,000 mbar. Still even yetmore preferably, for underwater applications, the pressure sensors usedhave an effective measurement range of least +/−45,000 mbar. Even stillyet more preferably, for underwater applications, the pressure sensorsused have an effective measurement range of least +/−50,000 mbar. Yetstill even more preferably, for underwater applications, the pressuresensors used have an effective measurement range of least +/−55,000mbar. Even yet still more preferably, for underwater applications, thepressure sensors used have an effective measurement range of least+/−60,000 mbar. Most preferably, for underwater applications, thepressure sensors used have an effective measurement range of least+/−65,000 mbar.

Ambient temperature sensors. The preferred temperature sensor is atypical thermistor known to those skilled in the art. However,innovative housings and deployment assemblies allow the temperaturesensor to be placed in various locations to measure various temperaturesof or surrounding the subject. One such housing for the temperaturesensor is preferably adaptable to attach in-line with a breathing tubefor airflow applications such as when attached to a breathing mask(e.g., for pilots and divers). In other words, when the temperaturesensor is used to measure the temperature of a breathing mix of gases asit travels through the breathing tube towards the subject's breathingmask, the housing connects in-line with that breathing tube, thusplacing the temperature sensor in the direct flow of the breathing mix.Such a breathing mix temperature sensor may be placed at the distal endof the breathing tube, or at the proximal end, thus effectivelyattaching to both the breathing tube and mask, or in series with theproximal end of the tube and other modular sensors. The housing may alsobe attached to the breathing mask on the exhaled breath side, thusmeasuring the temperature of the exhaled breath. Alternatively,temperature sensors may be placed in any combination of these locations,thus measuring the temperature of the breathing mix, inhaled breath,and/or exhaled breath in any combination. Additionally, temperaturesensors of any variety known to those of skill in the art may beincluded to measure ambient temperature of the environment surroundingthe subject. Ambient temperature sensors are particularly useful andimportant for underwater, and more particularly diver, applicationswhere the temperature of the surrounding water may have a significantand immediate impact on the subject's core body temperature, metabolicrate, and overall health condition.

Additional temperature sensors as described, or other varieties oftemperature sensors known to those skilled in the art, may be includedto measure various other temperatures related to the subject and thesurrounding environment. Thus, in addition to inhaled and exhaled breathtemperatures, other temperatures may be measured as well. A directmeasurement of the subject's core body temperature may be taken, or maybe calculated based on the inhaled and/or exhaled breath temperatures.Interior ambient temperatures may be measured in cabin, cockpit, orother such vehicle-employed systems, as well as exterior ambienttemperatures, or those outside of the cabin, cockpit, or the like. Fordiving applications, temperature sensors may be included to measureambient water temperature. In other words, temperature sensors may beincluded to measure the temperature of all gases inhaled or exhaled bythe subject, as well as any environmental or ambient temperaturessurrounding the subject, such that the conditions surrounding thesubject may be known and used to help monitor the subject's and system'sstatuses, as well as to detect or predict and mitigate or treatdangerous breathing conditions, and to help alert the subject or thirdparty.

Proximity sensors. Yet another type of sensor included in someembodiments of the present invention is a proximity sensor. Proximitysensors are used to detect the presence of nearby objects. Typically,proximity sensors emit an electromagnetic field or a beam ofelectromagnetic radiation (e.g., infrared), and look for changes in thefield or return signal. The object being sensed is often referred to asthe proximity sensor's target. Different proximity sensor targets demanddifferent sensors. For example, a capacitive photoelectric sensor mightbe suitable for a plastic target; an inductive proximity sensor issuitable for a metal target. The maximum distance that this sensor candetect defines its “nominal range.” Some sensors have adjustments of thenominal range or means to report a graduated detection distance.Proximity sensors can have a high reliability and long functional lifebecause of the absence of mechanical parts and lack of physical contactbetween sensor and the sensed object. Various types of proximity sensorsare known in the art, and the present invention could utilize any of theknown types in various embodiments. Several of such varieties ofproximity sensors include, but are not limited to, capacitive sensors,capacitive displacement sensors, Doppler effect sensors, inductivesensors, magnetic sensors, passive optical sensors, passive thermalinfrared sensors, photocell or reflective sensors, ultrasonic sensors,and the like.

Audio sensors. Audio sensors, such as microphones or auscultatorysensors, may be integrated into the present invention to provide controlinput from the subject, to collect data from the subject, or to acquireambient sound that is not recorded or collected but that may be passedthrough to the subject. For example, many forms of headphones andearbuds have noise cancelling features that operate by listening tosounds from the ambient environment and canceling out those sounds byintroducing inverse sound waves to the listener. However, there may betimes, as when jogging, driving, or riding a bicycle in traffic, that asubject may prefer to have ambient sounds more transparently passedthrough without being attenuated by noise cancellation. In such case,ambient audio microphones may pick up the ambient sounds and either passthem through without cancellation, or provide some intermediate measureof cancellation or transparency based on a user's preference as setthrough a user interface. Alternatively or in addition, certain ambientsounds may be selectively passed through based on their characteristics,such as frequency or tone, or their similarity to known noises. Thus,the device of the present invention could smartly and selectively passthrough doorbells, telephone rings, fire or theft alarms, emergencyvehicle sirens, car horns, screams, intelligible shouts, sounds ofbabies crying, and other alarming sounds, while smartly cancelling othernoises that are less likely to be intended to alarm or alert thesubject.

Preferably, in some embodiments the subject is provided with a userinterface by which he or she may adjust the level of noise cancellation,ranging from complete external sound inclusion, incrementally or on acontinuum up to more or less complete ambient noise isolation. In otherembodiments the subject is provided with a user interface by which he orshe may select, by characteristic, which types of sounds he or she wouldlike to have passed through more transparently, and which sounds he orshe would like attenuated by cancellation.

In addition to or instead of an ambient audio sensor, some embodimentsof the present invention may incorporate an ear bone microphone capableof picking up the speech of the subject through an earbud,advantageously allowing for hands-free two-way communication.

Video sensors. Video sensors, such as cameras, video cameras,electro-optical infrared camera combinations, or the like, may beincluded as a sensor of various embodiments of the present invention aswell. Video sensors of any variety can be used in conjunction with thepresent invention to provide or assist in proximity detection (e.g.,recognize when certain embodiments of the device are brought close tothe subject's face or donned upon the subject), record pictures or videoof the user and/or his or her surroundings while the system or device isin use, to provide movement or motion recognition (e.g., detect asubject's eye movement and adapt output or display of information basedon such eye movement), or other such uses for photographic or video datarecorded by such sensors.

Eye tracking sensors. Eye tracking sensors may be mounted on headgear(e.g., eyewear, the brims of hats, or in helmets) or may be placed on aseparate device such as a display, smartphone or other portableelectronic device, or on a dashboard or other vehicle or equipmentcontrol console. A basic eye tracking sensor may consist of only asingle video camera which is able to determine, to within an acceptabledegree of accuracy, where the eye(s) of a subject is/are looking, by,for example using an image matching algorithm or neural net algorithm todetermine if eyes are pointed straight toward the camera or at someangle away from the camera. In certain applications it may be acceptablefor such sensor to be only sensitive enough to make a binarydetermination (e.g., to determine only whether or not the subject hashis or her eyes on the road, and thus to keep statistics of the amountof time the eyes are on the road and from such statistics make adetermination of distracted or drowsy driving). More sophisticatedversions of eye tracking sensors use two video cameras and an infraredlight source and rely on a three-dimensional physiological model of thehuman eye. Infrared light from the IR source reflects off the pupil andcornea of the subject and is then captured by the two camera sensors.The collected images are processed to ascertain the position of the eyeand the direction of the gaze with higher accuracy. Eye tracking can beused not only to collect data, but for data manipulation, user interfacenavigation, and control of the device(s) of the present invention, aswell as for user identity recognition.

Eye tracking can also be done, to a limited degree, using data from EOGsensors.

Time sensors. Time is an important measurement in many fitness routineor activities and in many other occupational tasks. For example, it maybe important to know how long a jogger has been jogging in order tocompute the jogger's speed statistics, or how long a truck driver hasbeen driving in order to provide notifications or warnings that it maybe time for a rest. Methods of keeping time, for example in digitalwatch devices using an oscillating crystal such as quartz, are known inthe art. Time can also be ascertained or synchronized by connecting toan Internet time server. In some embodiments of the present invention,preferably, the system or device of the present invention automaticallydetects when an exercise routine or activity or occupational task hasbegun and automatically begins timing the routine. For example, throughanalysis of collected motion sensor and/or GPS data, it can bedetermined that a subject has woken up, set out on a run, begun abicycle trip, begun a long drive in a motor vehicle, or the like. Insome cases it may not be completely clear that the routine/activity/taskhas begun until several minutes or hours afterward. Once the system ordevice has determined that such an a routine/activity/task has begun,the system or device can examine past data to establish the beginning oroutset of the routine/activity/task and mark the beginning time. Thesystem or device may also establish the beginning of theroutine/activity/task through user input. The system or device can thenalso automatically determine the termination of theroutine/activity/task, for example, by noting a cessation of detectionof vigorous movement by a motion senor, or by noting in GPS coordinatesan arrival back home or at some other known destination. Given the startpoint and the end point of the routine/activity/task, the system ordevice may then, through appropriate subtraction, compute or estimatethe length in time of the routine/activity/task. Like the other valuesdiscussed in this application, this value may be stored, charted,reported, and/or used to provide notices or warnings to the subject.

Derived Measurements

A number of metrics may be computed, estimated, predicted, charted,and/or tracked in various embodiments of the present invention, based onmeasurements taken by the sensors of the present invention.

Heart rate. Heart rate (HR), also referred to as pulse, is commonlyknown to be the number of times a subject's heart beats in a timeperiod, the typical time period being one minute. Heart rate can bemeasured directly from the subject by physically sensing the pulsesattributed to the beats of the heart at numerous locations on thesubject's body; the best locations, according to the American HeartAssociation, being the wrist, inside of the elbow, side of the neck, ortop of the foot. However, such physical measurement of heart rate is notalways viable, particularly while performing other activities. It is notonly difficult to maintain pressure on the pulse point, count the beats,and maintain focus on the other activity or task, but it can bedangerous (e.g., a driver should not divert attention away from drivingto check his or her heart rate, nor should a person exercising, such ason a treadmill, divert attention from the treadmill and proper runningmotion to do so). Fortunately, heart rate can be monitored in automatedways as well. Heart rate monitors (HRMs) measure and monitor a subject'sheart rate, typically using either using a chest strap that placeselectrode sensors on the chest near the heart, or sensors of varioustypes placed in other locations such as on the arm or wrist. Existingsensors have various shortcomings related to their placement on the bodyand type of sensor that can result in inaccuracy, especially duringvigorous activity that has the effect of moving the sensor relative tothe body. Many available systems tolerate the loss of sensor accuracy byproviding estimations of heart rate when heart rate fails to becomereliably measureable, using guesses involving assumptions about themaximum rate at which heart rate may speed up or slow down. While lossof accuracy and supplementation of lost data through estimation may beacceptable to the casual user, increased accuracy and reliability is aperennial goal in sensor development.

Alternatively, as in the present invention, a subject's heart rate canbe measured far more accurately, precisely, continuously, and safely viaother methods. Specifically, the present invention acquires a rawelectrocardiogram signal from the subject which comprises the electricalbiopotential signals output resulting from the functioning of thesubject's heart. From this ECG signal, present invention extracts orderives a heart rate measure. This method is more accurate because it istaken directly from the ECG signal representing the heart's function,and does not rely on human intervention or requirements of simultaneousattention to counting beats and time while maintaining pressure on thepulse point. Further, this method is safer and more precise because theautomated, computerized processing means allows for the user to maintainfocus on whatever tasks or activities he or she is performing and doesnot require a splitting or sharing of attention between tasks and heartrate measurement—not to mention, again, the benefit of drawing the heartrate information directly from the ECG signal.

Deriving or extracting the heart rate from an ECG signal, however, doeshave some potential drawbacks. Often, physiological signals measureddirectly from a patient are subject to being corrupted by noise orartifacts from many different sources. Signal processing techniques,filtering, and other similar processes and methods allow for noise andartifacts to be removed, or for relevant, important portions of thesignal to be extracted or otherwise differentiated from the noise andartifacts, and thus allow for accurate and precise measurement of theimportant and relevant portions of the signal. Several such methods aredescribed at greater length herein, and are used with the presentinvention to ensure high quality, efficacious, accurate and precisesignal and data processing and analysis to provide the most accuratedata possible.

Heart rate variability. Heart rate variability (HRV) is directly relatedto the subject's heart rate, and refers to the occurrence of differingtime periods between heart beats. HRV is a measure of the variability ofthe beat-to-beat interval. HRV is thus effectively a measure of thereactivity of the heart to changes in metabolic need, and can be used toindicate dangerous conditions, usually as indicated by reduced ordecreased HRV, that warrant attention by the user and possibly a medicalprofessional. For example, decreased or reduced HRV is often associatedwith conditions or maladies including myocardial infarction, congestiveheart failure, diabetic neuropathy, depression, sudden infant deathsyndrome (SIDS), and has been found to occur after certain proceduressuch as cardiac transplants. Additionally, HRV has been correlated tovarious psychological conditions, such as stress. HRV is related toemotional arousal. High-frequency (HF) heart rate variability activityhas been found to decrease under conditions of acute time pressure andemotional strain and elevated state anxiety, presumably related tofocused attention and motor inhibition. HRV has been shown to be reducedin individuals reporting a greater frequency and duration of dailyworry. In individuals with post-traumatic stress disorder (PTSD), HRVand its HF component is reduced compared to normal while thelow-frequency (LF) heart rate variability component is elevated.Furthermore, unlike normal, PTSD patients demonstrated no LF or HFreactivity to recalling a traumatic event. A theory in medical circles,called Polyvagal Theory, derives from a psychophysiologic imputation ofimportance to HRV. This theory emphasizes the role of HRV inunderstanding the magnitude and nature of vagal outflow to the heart.This theory decomposes HRV based on frequency domain characteristicswith an emphasis on respiratory sinus arrhythmia and its transmission bya neural pathway that is distinct from other components of HRV, and isbased on anatomic and physiological evidence for a polyvagal control ofthe heart. Thus, HRV plays an important role in both physiological andpsychological human function, and monitoring or measuring HRV mayprovide valuable information and feedback to a subject and his or hermedical providers.

Variation in the beat-to-beat interval is a physiological phenomenon.The sinoatrial node (SA node) receives several different inputs and theinstantaneous heart rate or RR interval (referring to R as a pointcorresponding to the peak of the QRS complex of an ECG signal, and RR isthe time period between two successive R points) and its variation arethe results of these inputs. The main inputs are the sympathetic and theparasympathetic nervous system (PSNS) and humoral factors (thosetransported by the circulatory system), thus being closely related withthe galvanic skin response sensors discussed herein. Respiration givesrise to waves in heart rate mediated primarily via the PSNS. Factorsthat affect the input are the baroreflex, thermoregulation, hormones,sleep-wake cycle, meals, physical activity, and stress. Decreased PSNSactivity or increased SNS activity will result in reduced HRV. Highfrequency (HF) HRV activity (typically 0.15 to 0.40 Hz), especially, hasbeen linked to PSNS activity. Activity in this range is associated withthe respiratory sinus arrhythmia (RSA), a vagally mediated modulation ofheart rate such that it increases during inspiration and decreasesduring expiration.

Accurate estimation or calculation of HRV is highly reliant uponaccurate, continuous measurement of heart rate. If a single heart beatis not detected, and no smart algorithm is in place to interpolate themissing heart beat, the estimated or calculated HRV will be greatlyaffected by showing a very long interval between two successive beats asa result of the inappropriately or mistakenly missed beat. Even if asmart algorithm is in place to interpolate the missing heart beat, themissing heart beat may be interpolated in the wrong place and thus theHRV estimation or calculation may still be affected. Thus, it isimperative that the heart rate measurement must be precise, accurate andcontinuous. Methods involving determining heart rate from lightreflectance or transmittance have not to date been found satisfactory,given that such readings may be spoiled by light leakage and motionartifact during vigorous movement. Thus, preferably, HRV is determinedor estimated from heart rate data that is estimated or calculated fromdata sourced through ECG acquisition, preferably involving the removalor exclusion of artifacts and noise from the signal at its varioussuccessive levels.

There are many methods for determining heart rate variability, and theycan commonly be broken down into two distinct groups: time-domainmethods and frequency-domain methods, though other methods exist but areless commonly accepted. Time-domain methods focus on beat-to-beatintervals and analyze the time periods to obtain numerous variables thatdescribe the variability. Frequency-domain methods apply a transform tothe time-series ECG signal to convert it to the frequency domain andanalyze the frequency domain signal to determine the number of intervalsthat apply to each frequency band. Common signal processing methods forfrequency domain analysis can be used, including, but not limited to,power spectral density, fast Fourier transform (FFT), discrete Fouriertransform (DFT), and the like. Time-frequency analysis methods, such asspectrogram methods, and non-FFT parametric methods, including the Lombperiodogram (for non-uniformly sampled signals like R-R timeseries), theGoertzel algorithm, and time-frequency analysis comprising parametricDFT methods, may also be used.

Respiration rate.

Respiration rate is the frequency of ventilation, i.e., the number ofbreaths (inhalation-exhalation cycles) taken within a set amount oftime. Respiration rate can be determined from ECG using a variety oftechniques collectively called ECG-derived respiration (EDR). Two EDRtechniques found by the inventors to be most effectively implementedusing sensors attached to the head and/or arm are R-S modulation andrespiratory sinus arrhythmia (RSA). The R-S modulation technique fordetermining respiration rate from ECG relies on the fact that theelectrical dipole vector of the heart swings during inspiration andexpiration. In ECG, the amplitude between the R and S peaks of the QRScomplex changes based on the phase of this swing. By sampling andinterpolating the R-S amplitude for every beat, then detecting thefundamental frequency of this envelope, respiration rate can be derivedfrom ECG measurements. RSA, described above with respect to HRVdeterminations, is the speeding up and slowing down of the heart ratedue to inspiration and expiration. In RSA methods of computingrespiration rate, the R-R interval of the ECG signal is sampled toobtain an R-R time series (also called an R-R tachogram), and thefundamental frequency of the R-R tachogram is computed.

R-S modulation is computationally simpler, but RSA is more tolerant tonoise and artifact. The target algorithm would use a combination ofboth, perhaps relying exclusively on R-S modulation when the signal isclean to maximize computational efficiency.

Stress. Stress is generally defined as the response to a stressor orstimulus, and is an automatic response of the sympathetic andparasympathetic nervous systems reaction to the stressor or stimulus.Monitoring stress is effectively the process of monitoring a person'sresponse to environmental stimuli. The goal of such monitoring isultimately to, at a minimum, determine how a person reacts to a givenstimuli, and preferably, to help him or her address the stimulus andreaction safely and effectively, and to help the person return tohomeostasis, even in the continued presence of the stressor or stimulus.

Sleep cycle. Monitoring sleep cycle allows for the system or device ofthe present invention to determine the present state of consciousness ofthe subject, as well as to monitor and evaluate overall health, healthpractices and lifestyle of the user. Where sleep cycle data from manydifferent users can be aggregated and analyzed together for variousstatistical features, such data can yield insights about the habits andhealth of populations and subpopulations and can evidence how variousenvironmental or biological factors influence or interrupt such habitsor impact the analyzed groups' health. Such environmental factorsinclude seasonal changes in daylight, the workweek, the news cycle,cultural events like holidays and media sensations, natural or man-madedisasters, prevalence and frequency of drug use including depressantssuch as alcohol and stimulants such as caffeine, etc. Likely the mostsignificant biological factor in sleep cycle is the age of the subject,with older subjects having less sleep, but other biological factors mayinclude gender, genetic factors, and disease state of the subject. Sleepcycle data can also be analyzed, either on an individual basis or forpopulations, to learn how sleep cycles correlate with or causedisorders. For example, it is believed that ADHD may result frominterruptions in a regular bedtime schedule, and that clinicaldepression correlates with abnormal sleep patterns.

Sleep cycle can be derived or estimated from data from a variety ofsensors or by combining data from such sensors. Data from body-mountedGPS sensors, for example, can provide a crude estimate of sleep cycle ifassumptions are made that a subject who has not moved for a certainperiod of time, and appears to be in a safe dwelling place, is asleep.However, these assumptions fail when the person is stationary withoutsleeping (as when working at a desk or even while in bed) or when thesubject is sleeping while in motion (as when sleeping on an airplane ortrain). Data from motion sensors can provide a better substitute or asupplement for such data, as stillness is consistent with sleep, butstill cannot ascertain with certainty that a subject is asleep. Datafrom electroencephalogram (EEG) sensors provides a still bettersubstitute or supplement for the aforementioned data sources, assleeping subjects exhibit clearly different brainwave patterns. Videoand/or audio may likewise be used as substitutes or supplements for theabove. In some instances, even the absence of sensor data may beinterpreted as indicating sleep if it is assumed that the subject onlyremoves the body-mounted sensors of the present invention to sleepcomfortably. It is contemplated that any sensor known in the art for thepurpose of ascertaining sleep cycles may be used in the presentinvention so long as it is small and lightweight, consumes sufficientlylow power, and may be worn and carried by the subject.

Alertness/concentration/focus. Alertness is a measurement derived fromsignals of the various sensors that relates to the subject's level offocus, consciousness (similar to detecting sleep stage), awareness ofthe surroundings, and attention to a particular activity, task, object,or other such focal point. For example, an alertness metric allows thesystem or device of the present invention to determine whether thesubject is daydreaming or otherwise losing focus on a particular task athand, such as driving, reading, or working. Alertness can be derivedfrom a single sensor measurement, such as an EEG, but in most instancesis best determined by a combination and fusion of multiple sensormeasurements, for example EEG in combination with eye tracking, thoughother combinations may work as well.

Preparedness (stress+alertness). Preparedness is another metric that isderived from one or more sensors, and is essentially a combination ofother, individual metrics the system or device may determine in variousembodiments. For example, preparedness may be a combination of stressand alertness metric used to detect whether the subject is awake,focused and attentive to his or her surroundings or task, as well as theamount or level of stress the subject is experiencing. The preparednessmetric may have particular utility for military applications such as forsoldiers in the field, sports applications for players who may havesuffered a potential concussion, first responders who can apply thesystem or device to injured parties, or the like. The preparednessmetric would also provide utility for the casual user or workenvironments as well.

Calorimetry. The number of calories burned during a particular exercise,activity, workout, or other period is a common metric used in varioushealth tracking devices, heart rate monitors, lifestyle managementdevices, and the like. Calories burned may be estimated throughknowledge of the type of physical activity engaged in, the duration ofthe activity, and personal information about the subject such as age,weight, height, gender, and the like. The information about the subjectmay be input by the subject while the knowledge of the type of physicalactivity engaged in and the duration of the activity may likewise beinput or more preferably may be derived from GPS and/or motion sensordata (from accelerometers and/or gyroscopes), or from data transmittedfrom other devices such as treadmills or exercise machines. Motion andparticularly the strength and frequency of detected body impacts may beanalyzed statistically to classify time periods as running, jogging,walking, bicycling, rowing, performing calisthenics, resting, etc.

In some embodiments the present invention may be used to measure basalor resting metabolic rates or calories burned or metabolic rate during aparticular activity or time period. With the user input and metricsmeasured or derived from the sensors of the system or device, the systemor device can then calculate the various calorie or metabolic metricsand provide the information to the user. Preferably, the output iscomputed from known common formulas for calculating calories burned,which may be different for men and women. More preferably, the output iscomputed using statistical analyses and with the aid of a database ofphysical activity data generated from numerous subjects of varying ages,genders, heights, and weights. Many different methods or formulas areknown in the art and can be used with the present invention.

Metabolism/indirect calorimetry. A number of other metrics useful forgauging sports fitness or overall health may also be estimated,computed, predicted, charted, and/or tracked over time based on thesensor measurements taken and recorded by the present invention. Oxygenconsumption (VO₂) or maximal oxygen consumption (VO₂ max) can be gaugedin one of the various mask embodiments of the present invention with theuse of an oxygen sensor, or may be more simply estimated, even withoutcompletely taxing the aerobic energy system of the subject, using one ormore of a variety of estimations known in the art, such as theUth-Sørensen-Overgaard-Pedersen estimation, the Cooper test, or theLeger-Lambert multi-stage fitness test. Other metrics that can besimilarly estimated or computed and tracked/charted for the subjectinclude carbon dioxide production (VCO₂), energy expenditure (EE) (i.e.,heat production), respiratory quotient (RQ), and substrate utilization.

Advanced recommendations. The system or device of the present inventionmay further provide notices or warnings to the subject upon detection ofvarious conditions relating to the measurements or estimated orpredicted metrics. Such notices may serve as motivators or enticements,especially when based on predicted metrics, and/or may serve to “unlock”various personal “achievements” to assist the subject in meeting fitnessgoals. For example, the device or system of the present invention maydeliver a notice to a jogging subject that if the jogger jogs one moremile at the present rate, the subject will set a new personal speedrecord for his or her jogging routine. The subject, receiving thenotice, may then be motivated to maintain or increase pace in order toset the new record. As another example, the device or system of thepresent invention may deliver a notice to an exercising subject when arecent meal has been “worked off” through exercise by gauging the numberof calories of energy expended during an exercise activity or routineand comparing this number to the number of calories consumed in themeal. The number of calories consumed in the meal can either bepre-input by the subject through a user interface, or determined byautomated methods. As one example of an automated method of determiningthe caloric content of a meal, the user may scan a barcode or QR codefound on the packaging of the meal, or other identifying packaging ordescriptive labeling, with a smartphone camera or similar scanningdevice linked with or incorporated into the device or system of thepresent invention, and the caloric content of the meal is then retrievedfrom a database for comparison. In a similar example, the user could benotified when a sufficient number of calories have been expended (or areabout to be expended) to justify consumption of a reward meal or snack,where the reward meal or snack may be one known to be a favorite of thesubject (either from input preferences or from information harvestedfrom social media) or one provided as a promotional advertisement from asponsor manufacturer or restaurant. An enticement may include theactivation or unlocking of a coupon for a food product or other item orservice. Other advanced recommendations may include, without limitation,notifications of when it is time to begin or cease an activity, when itis time to rest or go to sleep, when it is time to wake up, when bodilyfatigue is imminent, when activity or relaxation should be engaged in toprevent or forestall a hazard condition (such as a pressure ulcer, jointirritation, or the like), and similar. The advanced recommendations mayappear as text on a display, as verbal announcements supplied throughsoundspeakers, as any combination of text, graphics or motion imagessupplied on a video display, or in any other fashion. These are but afew examples of advanced recommendations that may be provided to asubject making use of the device or system of the present invention.

The device or system of various embodiments of the present invention mayalso devise and propose tests or experiments for the subject toundertake which may make use of the scientific method to eliminatevariables and thereby settle on the true causes of certain conditions,or, alternatively, may analyze already-collected data to carry outlargely the same scientific function without the need for alerting thesubject that the test is to be conducted. For example, if the subjectreports to the device or system an undesired feeling or sensation, andthe device or system is provided with information about the diet of thesubject and has also collected exercise activity data, the device orsystem can test the effects of the known various dietary choices andexercise activities with the feeling or sensation by testing forstatistical correlations between the various dietary/exercise inputs andthe feeling/sensation results as reported at various times over aperiod. A database of test regimens may be supplied to the device orsystem through, for example, the Internet, and may be customized by thedevice/system for the individual subject, allowing the device/system totell the subject to engage or refrain from certain dietary choices orexercise activities during certain periods so as to complete the neededdata collection and promote the analysis. Thus, for example, thedevice/system can test the effects of subject choices on the subject'smetabolism, and then recommend those activities or comestibles thatincrease or decrease metabolism as desired by the subject.

An advanced assisted heart rate training program is another example of afunction that may be provided by the device or system of the presentinvention in various embodiments. Although heart rate training can bedone with simpler heart-rate monitors, doing so requires significantunderstanding, thought, and computation on the part of the individualtrainee. The present invention simplifies the training by supplyingsimple instructions and suggestions and providing easy-to-understandquantitative summaries of collected data. In heart rate training, bymaking use of measurements during activity and while at rest, the deviceor system of the present invention can assist the subject in fine-tuningphysical activity, especially high-intensity activity such as running,by making suggestions and giving instructions that lead the subject toengage in the optimal intensity of the activity.

Heart rate training involves, at the outset, the device or systemestimating or determining the subject's heart rate response to variousactivity intensities. Three heart rates are of special interest: theresting heart rate, the lactate threshold heart rate, and the maximumheart rate.

The device or system estimates the subject's resting heart rate bymeasuring the subject's heart rate at an appropriate time, such as whenthe subject wakes up prior to getting out of bed, or more preferably bycomputing a rolling average of such measurements collected over a timeperiod, such as the last week or the last month, with outliers omittedfrom the computation. This can be determined automatically and nospecial instructions are needed to be provided to the subject, so longas the subject can comfortably wear the sensors of the present inventionto sleep, or is instructed to don the sensors immediately upon waking upwithout exerting substantial physical effort.

The device or system determines the subject's lactate threshold heartrate while the subject is exercising at an intensity at which lacticacid accumulates in the blood stream, an intensity level generallycorresponding to the highest intensity of activity that can be sustainedwithout the subject experiencing significant discomfort and a largeincrease in breath rate. The device or system provides the appropriateinstructions, encouragements and enticements necessary to impel thesubject to perform such activity. For example, the system may instructthe subject to jog at a comfortable pace for two or three minutes, thento increase and sustain pace slightly for another two or three minutes.When the system notes a spike in breathing, either through sensorscapable of detecting breath rate, or through user input of such a spike,or most preferably through ECG methods of detecting respiratory rate asdescribed above, the detected heart rate at the previous level ofactivity intensity is deemed the lactate threshold heart rate.

The device or system estimates the subject's maximum heart rate byselecting the maximum heart rate detected from the subject during aparticular activity designed to elicit all-out physical effort. Examplesof such activities include running a competitive 5-kilometer race, or2-mile time trial at maximum sustainable effort on a track or a roughlyflat stretch of road. As before, the device or system provides theappropriate instructions, encouragements and enticements necessary toimpel the subject to perform the particular activity. Alternatively, thedevice or system can estimate maximum heart rate using a formula thattakes into account subject-input factors such as age and fitness level.One simple formula subtracts the subject's age from 220 to arrive at anestimated maximum heart rate.

The device or system can compute the subject's heart rate reserve bysubjecting the subject's resting heart rate from the subject's maximumheart rate.

With these values established, the device or system of the presentinvention devises work-out routines and work-out schedules based onpre-defined templates, the subject's preferences, measured or estimateddata collected from the subject during workouts, and/or statistical datacollected from or representative of other trainees, and preferably othertrainees similar to the subject in age, fitness level, and otherfactors. The individual work-out routines induce the subject to exercisefor a time period less than a day within a variety of target heart rate“zones,” while the work-out schedules alternate more challenging withless challenging work-out routines over a time period of weeks, months,or years to encourage regular physical activity and promote overalllower subject heart rates, both maximum and resting, indicative ofhealthy and sustainable cardiovascular development. The work-outroutines and schedules are presented to the subject through theaforementioned instructions, encouragements and enticements, as well as,optionally, through modification of the subject's personal calendar toinclude work-outs scheduled at convenient times, as permitted by thesubjected. The device or system can advise the subject when “It's timefor your daily workout,” for example, and can suggest automaticrescheduling of the workout if it appears from sensor measurements thatthe subject is not performing the workout.

Examples of various zones can be warm-up or recovery zones at 60 to 70percent of heart rate reserve plus resting heart rate; aerobic zones at70 to 80 percent of heart rate reserve plus resting heart rate;anaerobic zones at 80 to 90 percent of heart rate reserve plus restingheart rate; and extreme or “red line” zones at 90 to 100 percent ofheart rate reserve plus resting heart rate, the last of which involveslactic acid buildup and thus should be programmed for only short periodswithin a work-out routine. When it is time within a work-out routine fora transition to a more or less challenging zone, the device or systemprovides an instruction or notification to the subject to “pick up thepace” or “slow down,” for example; determines the subject's heart rateand/or other parameters of interest, and issues a follow-up instructionor affirmation to induce the subject to adjust or maintain activityintensity so as to transition to or stay within a target zone accordingto the pre-defined work-out routine.

An example of a simple work-out routine template is as follows: 10minutes of warm-up activity, targeting a first heart-rate zone; followedby 10 minutes of more intense activity targeting a second heart-ratezone; followed by 5 minutes of maximum intensity activity, targeting a“red line” zone; followed by 10 minutes of cool-down activity, targetingthe first zone again. Innumerable such templates can be devised andrevised using known methods, and can be refined to meet the subject'sfitness goals and workout preferences as the subject's physical fitnessapparently improves with reference to fitness statistics collected fromcomparable populations and provided to the system or device through,e.g., the Internet.

In similar fashion, with or without the above-described training, thedevice or system of the present invention can provide testing todetermine subject preparedness for a goal activity or mission.Preparedness in this context is defined as the apparent physicalability, including speed, endurance, stamina, etc., to complete aphysical task, such as finishing a marathon or triathlon, completing ahike or mountain climb, participating in a strenuous military mission ortraining exercise, staying awake and alert for a long drive, or thelike, as determined by testing the subject either underactivity-simulating conditions or under conditions which are known tocorrelatively demonstrate preparedness. In such a way, the device orsystem can advise the subject or the subject's superior or regulatorthat the subject is or is not prepared to run the marathon, complete thehike, fly the mission as a pilot, etc. based on quantitatively collecteddata and known activity requirements. For example, if the device orsystem is supplied with the known resting heart rates and maximum heartrates of race qualifiers, the device or system can evaluate the subjectas prepared or unprepared for the race based on its measurements orestimates of the same parameters for the subject, and then furtheroptionally suggest a training regimen, as described above, to maintain,improve, or achieve the subject's preparedness.

Actuators

Haptics. Haptic technology provides tactile feedback that stimulates thesense of touch by applying forces, vibrations, or motions. Hapticactuators include vibrators, as are common in cell phones and video gamecontrollers, and actuators that suppress motion, as by locking joints orpressing against limbs. A simple vibrator is made with an eccentricrotating mass (ERM), which involves a mass spun by a motor on an axisoff its center of mass. Different effects (and thus differentdistinguishable signals to the user) can be created by pulsing the spinswith different durations, pulse frequencies, and/or duty cycles, and/orby altering the spin speed. More advanced vibrators use linear resonantactuators (LRAs), which vibrate a magnet attached to a spring andsurrounded by a coil when current is applied, or piezo beams or disks,which deform on the application of current. Different effects (anddistinguishable signals) can be achieved with these actuators as withERMs. The present invention further envisions haptic actuators thatfunction by pressing or vibrating against pressure points, for example,by pressing against or massaging one or more temples of the head toautomatedly relieve maladies such as migraine headaches, nausea, andseasickness upon detection of such a malady or upon being informed ofsuch a malady. These haptic actuators may be incorporated in the eyewearor other headgear of the present invention.

Shock. Electrical stimulators use electrodes to deliver mild electricalcurrents to parts of the body. Stimulation is typically applied as aseries of pulses. Insufficient current density will have no appreciableeffect as it will not innervate the target neurons to bring about thedesired signal to the subject, but too much current density, or currentdensity applied over too long a period of time, can cause hyperthermiato tissues, damaging them. Electrical stimulation pulses should beapplied in a safe manner so as not to damage tissue. The safety of theelectrical stimulation depends on a number of factors, including theduration and number of pulses and the size of the electrodes with whichthey are applied, as well as tissue impedance and the ability of tissuesto quickly transmit away heat energy. Where the electrodes are small andact as point sources of current, the damage threshold is determined bythe total current, whereas with larger-diameter electrodes, the damagethreshold is determined by current density, which scales with pulseduration as the reciprocal square root of time of pulse. Methods andcomputations known in the art for supplying safe, effective electricalstimulation should be employed and caution should be exercised whenusing stimulation. In the embodiments of the present invention, the riskof life-threatening stimulation is lessened through use of small batterypower for any stimulator and by the absence of stimulator current pathsthrough the heart.

Light actuators. Certain other actuators permit for gradual or morerapid changes in the environment of the subject, including ambientlight. In the cases of eyewear and masks, for example, small lights suchLEDs or other light emitters may be placed in proximity to the eyes andmay glow, flash, or blink. Preferably, this placement is along thediameter of lenses on the inside of the eyewear frames. Alternatively,larger light emitters (LEDs or otherwise) placed elsewhere and adaptedto be in communication with the present invention may be used to providenotices or warnings by illuminating, de-illuminating, flashing, etc.Alternatively, visors, lenses, and goggles may be made with anytechnology known in the art to be capable of electronically tintingglass or plastic lenses or visors, and thus to permit outside light toslowly (or quickly) enter from an initial darkened state. One suchtechnology is the AlphaMicron E-TINT technology, which use a mixture ofdichroic dyes in a liquid crystal host sandwiched between flexibleplastic substrates coated with transparent electrodes. With thistechnology, transmissivity and color are changed when voltage is appliedto the substrates and an electro-optic response is induced in the liquidcrystal; the tint can be fully activated in about half a second. Inembodiments of the present invention involving eyewear, such lights ortinting actuators can gradually increase light stimulus delivered to thesubject over time, as with a graduated alarm clock, or may provide morerapid light changes to alert the subject to an alarm condition or torouse the subject from a drowsy state.

Soundspeaker. A soundspeaker can provide sound signals, including musicor speech, to the subject, for example, as implemented in earphones usedin headphones or earbuds, or as implemented in some other device placednear the subject, such as a smartphone, car stereo, alarm clock, orentertainment system. If a soundspeaker is not implemented directly inthe device of the present invention, the device can communicate thesounds to be produced, or transmit instructions to produce sounds, to anearby device on a wired or wireless connection, including Bluetooth,WiFi, or any other protocol known in the art. As described above withrespect to light actuators, it may be desirable in certaincircumstances, to produce a sound signal of gradually increasingintensity in order to more gently alert or arouse the subject.

Computer interface/video screen/UI. Many embodiments of the presentinvention include a visual display or other visually-stimulating system.Various types of devices are known in the art for generating a visualsignal, even in miniature systems that are worn on the head or the eye.In some embodiments, the display may consist of a video monitor, setapart from the device of the present invention, which the device maysend (and in some cases receive) signals to (and from). In otherembodiments, the display may be similarly separated from the device ofthe present invention but may be integrated into an interfacing devicesuch as a digital music player, PDA, smartphone, watch, health monitordevice, or the like. In other embodiments, particularly those involvingeyewear, the display is integrated into the device of the presentinvention, in which case it is preferably small enough to be worncomfortably on the body, and preferably as a head-mounted display (HMD),as with the displays now in use on smart eyewear devices such as GOOGLEGLASS and similar devices. Such embodiments may employ one or more of anumber of different display technologies, including a heads-up display(HUD) accomplished through (1) a liquid crystal display implemented inan eyewear lens; (2) projection onto a transparent prism situated in thesubject's field of vision; (3) an optical waveguide (diffractive,holographic, polarized, reflective, etc.); and/or (4) a virtual retinaldisplay (VRD), also known as a retinal scan display (RSD) or retinalprojector (RP), which draws a raster display onto the retina of the eyeusing one or more beams of coherent light. In any instance, the displaypermits the perception of a “hovering display” of generated imagesoverlain on the subject's vision of the real world. In suchimplementations, the resolution of the display is preferably at least640 by 360 pixels.

Temperature actuators. Some embodiments of the present invention mayalso communicate to a temperature control device, such as a heater, airconditioner, or miniature thermal actuator, to provide a temperaturechange or temperature signal to the subject. For example, if an unwanteddrowsiness condition is detected in the subject, an appropriateembodiment of the present invention may send a signal to a vehicleclimate control system to adjust the temperature (e.g., to switch on theair conditioning) in order to ameliorate a drowsiness-inducingtemperature, or may activate a miniature temperature actuatorincorporated in the device or placed nearby on the body of the subjectto send a cooling or warming feeling that is effective to rouse thesubject or to alleviate discomfort or pain that the device has eitherdetected or been alerted to.

Ear pressure equalization. In some embodiments of the present invention,and particularly those which use earbuds or similar devices which mayclose off the ear canal to the outside world, preferably such devicesinclude an actuator to opens a passage to equalize the pressure betweenthe ear canal and the ambient environment. The actuation is felt by thesubject as a puff of air to “pop” subject's ear. Such an improvement isimportant where the subject may be gaining or losing altitude, as inaerospace applications, standard air travel, mountain climbing, and forpersons who work on tall buildings or in deep mine shafts and may travelon elevators. Such an improvement prevents the subject from needing toremove the earbuds or similar devices in order to achieve the relief ofair pressure equalization in the ear(s).

Power and Energy Harvesting

The device embodiments of the present invention are preferably small,lightweight, and totally portable, meaning they can be comfortably wornon the body and carried with ease. Power is provided to such embodimentsby a small battery. Preferably, the battery is replaceable and/orrechargeable. The battery technology may be selected from any suitabletype known in the art, including replaceable alkaline or replaceablerechargeable such as nickel-cadmium or nickel-metal hydride,lithium-ion, lithium polymer, etc. Especially in embodiments thatinclude a wired data transfer port such as a USB connection, the batterymay be advantageously recharged using the same cable as the one used fordata transfer and during the same time as data transfer, using powerconnections in the transfer cable. Inductive methods of power transferknown in the art and implemented in a number of sealed rechargeabledevices may also be advantageously employed for recharging the deviceembodiments of the present invention.

More preferably, the device of the present invention is capable ofsupplementing its energy supply by harvesting energy from the subject orthe environment. Photovoltaic, piezoelectric, and biomechanical-kineticmethods for energy harvesting are known in the art and may beadvantageously employed in the present invention. For example, a ballcapembodiment of the present invention may collect solar energy using aflexible photovoltaic surface applied to the cap and brim to supplementits battery charge, while a wristwatch or eyewear embodiment mightutilize the kinetic energy of the body or a limb during movement to winda mainspring or to move a magnet in an electromagnetic generator toproduce supplementary energy.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1A, 1B and 1C illustrate an earbud embodiment of the presentinvention, in which sensors 12, 16 are mounted along the outside rim 13of the earbuds 11. As illustrated, dry electrodes 12 incorporatingsurface features such as bumps or penetrators are used to acquire ECG orother electrophysiological signals. The surface features improve thequality of the acquired signals and/or assist to keep the earbud securein the ear, thereby also improving acquisition during vigorous activityby reducing motion artifact and loss of sensor contact with the skinthat can result from jostling. Other sensors 16 may be infrared or ofany other suitable type listed above in this application. The earbud 11further incorporates a soundspeaker 18 through which music, speech,instructions, notifications, warnings, or reports may be delivered. Insome embodiments the tempo of the delivered music may be adjusted to thepace of the subject's physical activity, e.g., delivered music may besped up as a jogger runs faster, as detected by motion sensor data, GPSdata, heart rate measurements or estimates, or measurements from orestimates based on any other suitable sensor or suite of sensors.

Use of two electrodes permits the ECG to be measured based on two pointson different sides of the head. A third electrode can provide a groundor reference. The third electrode can be implemented in the earbuds (asillustrated) or in some embodiments may be placed elsewhere on the body,like on the torso or arm, and in such case may be integrated into aseparate device such as a music player, smart phone, watch, etc.

Preferably, rim 13 is made of an electrically insulative material so asto keep the electrophysiological sensors 12 electrically isolated fromone another. The rim may be made of a non-toxic silicone polymer or aharder plastic. Preferably the rim fits in the ear so as to provide agood seal and to keep the earbud anchored.

The earbuds may receive audio from a separate device (24, 25, 26 in FIG.2) or may have a built-in digital memory (not shown), preferably anon-volatile flash memory, for digital storage of media files.

Optionally, the earbuds may be connected to each other and/or to aninput and/or output device (such as a digital music player, smart phone,or health data monitor) by wire 14. In some embodiments, preferably,wire 14 is a mere tether to keep the earbuds together physically. Insuch embodiments, or in other embodiments in which there is no wire 14,the earbuds preferably communicate with each other and/or with anotherdevice using a wireless protocol such as Bluetooth or WiFi to transmitdigital audio and acquired sensor measurements. In other embodiments theearbuds may be tethered together (with wired signal connection or not)by a more rigid connector 27 that fits around the head and helps to keepthe earbuds snugly in place (as shown in FIG. 2).

Preferably, the earbuds also have one or more of the other above-listedsensors incorporated into the housing 11, such as MEMS motion sensors(accelerometer/gyroscope) (not shown).

Data collected by sensors may be recorded to a non-volatile flash memoryor other memory incorporated into the earbuds (not shown) or to one ormore of the connected devices 24, 25, 26, and may be retransmittedwireless or transferred through a wired feed, such as by USB, at a latertime, for storage or analysis on another computer or device (not shown).Preferably, the battery of the earbud may also be recharged eitherthrough a USB connection or through an inductive power transfer.

In alternate embodiments, headphones with integrated sensors are usedinstead of earbuds, with the dry electrodes and/or other sensors placedon the rims and/or insides of fitting headphone earcups so as to pressagainst the skin and provide good electrical contact and lower motionartifact.

As shown in FIG. 2, the different styles of earbuds 21, 22 may either bewired (21) or communicate wirelessly 23 (22) with one or more otherdevices worn on or placed near the subject's body during the fitnessroutine/activity or occupational task. These may include a digital musicplayer 24, watch or smart watch 25, smart phone 26, or other electronicdevice such as a PDA, health monitor 31, etc. As shown in FIG. 3, healthmonitor 31 may be a small electronic device with a display screenshowing measured, computed, estimated, derived, or predicted metrics andpreferably also including a user interface to scroll through and/orcustomize the metrics displayed. Preferably, a clip 32 is provided toclip the health monitor to the clothing of the subject, or an armband,chest band, or headband. As mentioned previously, the health monitor mayfurther include additional sensor(s) of the types already discussed. Adry electrode incorporated in the monitor 31 or its clip 32 may serve asa ground or common electrode.

FIG. 4 shows another embodiment of the present invention consisting ofsensors implemented in wireless earbuds 42 useful for detecting whetherthe subject is drowsy or alert, focused or unfocused during anoccupational task such as driving a vehicle or operating dangerousmachinery such as heavy construction equipment or factory equipment.Such sensors preferably comprise ECG, EEG, motion, and/or temperaturesensors, as well as ambient and/or ear bone microphone(s). During normaloperation the earbuds may deliver music and/or keep the subject inone-or two-way radio communication with a home base. Optionally, sensed,computed, estimated, or predicted statistics or metrics may be displayed40 for the subject or may be transmitted back to a home base, providingsafety-related feedback to supervisors. Upon detection of a conditionsuch as a reduced heart rate, a change in brainwave pattern(particularly a transition from beta to alpha, theta, or delta waves) ora combination of conditions such as lack of substantial motion over apredefined threshold period of time in combination with temperatureabove or below a threshold (indicating possibly sleepiness), anotification or warning 41 may be delivered to the subject, eitherthrough a visual display (in a moving vehicle, preferably this is aheads-up display incorporated into the dashboard and/or windshield) thatis in communication with the earbuds through a wireless connection,and/or through an alarm or speech message delivered through the earbudsor other audio device. The present invention may further trigger thedriven vehicle to initiate automatic braking, automatic steering, orother autopilot features, or may trigger any other equipment to shutdown and/or put itself in a less dangerous state, eithercontemporaneously with the notification/warning to the subject, orwithin some predefined period of time thereafter, or if thesystem/device determines that the notification/warning has beenineffective in focusing or rousing the subject by sensing thepersistence of the drowsy or unfocused state and/or the lack ofappropriate response to the notification/warning. As discussed earlier,the notification or warning may be delivered as a visual or audiblestimulus or as a temperature change using a temperature actuator or as amild electrical signal using a stimulating electrode, or as any othersuitable type of stimulus such as those discussed previously in thisapplication. Although FIG. 4 shows earbuds 42, it is envisioned that anyof the headgear or eyewear embodiments may be implemented to similareffect in a drowsy-driver, impaired-driver, or distracted-driver warningsystem.

Rather than using earbuds for the same or similar application, eyewearas shown in FIGS. 5A-5C or 5D-5G may be used. The eyewear 51 asillustrated in FIGS. 5A-5C incorporates earbuds 52 attached to theeyewear by wires 53, but the earbuds may be wireless and interface withthe eyewear or another device by means of a wireless protocol, or theearbuds may be omitted entirely and the device may be limited to theeyewear only (not illustrated). Sensors, and in some embodimentspreferably dry electrophysiological sensors 54 having surface features,may be integrated into the temple stems 55, the nose bridge 57, or nosepads (not shown) to detect electrophysiological signals from the head ofthe subject. These and other sensors may be implemented at anyappropriate place on the eyewear frames, but particularly in the case ofelectrophysiological sensors, the sensors are advantageously placed atpoints where the frames provide natural pressure against the skin of thesubject—especially along the temple stems and nose bridge. Measuredvalues, calculated/estimated/predicted statistics, notices or warnings56 may be delivered to the subject in the subject's field of visionusing any of the HMD technologies discussed above or by any other methodknown in the art. Depending on the particular embodiment, lenses may bepresent or omitted depending on the display technology used or omissionthereof. If earbuds 52 are incorporated, or if another audio device ispresent nearby, audio notifications or warnings may be delivered aswell. Other sensors may also be integrated into the glasses, such asMEMS motion sensors, to provide any of the aforementioned dataacquisition or to drive a user interface controlled through headgestures/postures/motions such as nods, tilts, or shakes. If necessaryadditional frame housing 58 may be provided to house sensor(s),processor(s), actuator(s), and associated electronics (foramplification, processing, and transmission of collected signals, forthe subject's interfacing with the eyewear device, for display orfeedback, or for wired or wireless transmission or storage of data onthe frames of the eyewear. Preferably the weight of these components isdistributed symmetrically on the eyewear. Preferably, the electronics,sensors, and other components are integrated into the eyewear frames asclosely as possible and with the edges being smoothed so as to avoid anungainly boxy appearance and provide a more natural style. In someembodiments, preferably, dry electrophysiological sensors forward on thetemple stems and nearer to the eyes are used to collect EOG signalswhile dry electrophysiological sensors back on the temple stems over theears are used to collect ECG signals. The inventors have found that thisarrangement is particularly well adapted to collecting EOG and ECGsignals from the head. EOG signals can be used to detect eye movementsand blinks which in turn can be used to drive the user interface of thesystem or device. For example, a detected double-blink, or blinks orcertain duration or intensity, can be programmed to perform certain UInavigational tasks, such as substitutes for mouse clicks or fingerpoints in more traditional user interfaces, while estimated or derivedeye direction or orientation can be used as a substitute for a pointerin more traditional user interfaces.

In embodiments illustrated in FIGS. 5A-5C, the dry electrophysiologicalsensors are round and have radially-symmetrical arrangements of surfacefeatures, but in some embodiments, preferably, the electrodes are shapedto be elongated and to have linear arrangements of surface features,e.g., one or two rows of bumps or penetrators extending along the templestems. Such an arrangement permits for temple stems to be naturally thinwhile still providing sufficient room and surface area for the dryelectrophysiological sensors. In any case, the shape and fit of theeyewear naturally provides sufficient pressure to press the dryelectrophysiological sensors against the skin of the subject to maintaingood electrical contact, particularly in conjunction with the action ofthe surface features, which assist in holding the electrodes in placeagainst the skin, even during vigorous activity, ensuring a minimum ofmotion artifact. The disclosed arrangements are capable of producingclean ECG solely from the head even when the subject is moving his orher head vigorously.

Another eyewear embodiment is shown in four different views in FIGS.5D-5G. This embodiment has four dry electrodes 54 a, 54 b, 54 c, 54 d,each with a linear arrangement of bumps or penetrators which variouslymake contact with the skin above the ears (54 a, 54 d) or at the templesnearer the eyes (54 b, 54 c) on both the left (54 c, 54 d) and right (54a, 54 b) sides. This configuration provides good contact and signalcollection even through the hair of the wearer. Additional sensors,including other dry electrodes, temperature sensors, galvanic skinresponse sensors, NIR sensors, and/or pulse oximetry sensors may beimplemented in the nose pads 59 and thereby make good contact with theskin. A head-mounted display (HMD) 56 a provides visual information,including instructions, to the wearer. Additional frame housing 58 a maybe provided to house sensor(s), processor(s), actuator(s), andassociated electronics (for amplification, processing, and transmissionof collected signals, for the subject's interfacing with the eyeweardevice, for display or feedback, or for wired or wireless transmissionor storage of data on the frames of the eyewear. Preferably, the weightof the eyewear is balanced symmetrically across the wearer's head forcomfort. There may or may not be lenses (not shown).

Other in-the-ear embodiments of the present invention are shown in FIG.6 and FIGS. 7A-7B. Operating similarly to the earbud embodimentspreviously described, the wired or wireless in-ear hearing aid 61 ofFIG. 6 advantageously incorporates one or more sensors as describedabove, preferably including dry electrode(s) preferably having surfacefeatures. The hearing aid 61 may fit to the concha of the ear and/or mayalso partially fit into the outer ear canal of the subject to provideadditional fit and security from motion artifacts and/or to placesensors (e.g., for measuring temperature) further in the ear canal andcloser to the eardrum. Wireless or wired earbuds 71, as shown in FIGS.7A-7B, may also be custom-molded to perfectly fit the ear of thesubject, including concha and/or outer ear canal, using anycustom-molding fabrication method known in the art, including by takingcasts of the subject's ear(s) and/or by laser scanning measurementand/or other photogrammetric measurement. A custom-molded earbud has theadvantage of providing an even closer, tighter fit that is capable ofwithstanding even more rigorous physical activity and jostling, and thusproviding even higher-quality signals.

FIGS. 8 and 9 show helmet embodiments of the present invention, with thedry electrophysiological sensors 81, 91 (preferably having surfacefeatures as described previously) and other sensors, actuators, andfeatures of the present invention incorporated into sports helmet 82,92. Interior padding provides a tight, comfortable fit and the necessarypressure to keep the dry electrodes 81, 91 pressed against the skin soas to make good electrical contact and to reduce or eliminate motionartifacts.

FIGS. 10 and 11 show hat and cap embodiments that function similarly tothe already-disclosed earbud, eyewear, or helmet embodiments. FIG. 10shows a head-formed, tight-fitting headwear such as a swim hat or showercap 101. FIG. 11 shows a baseball cap 111. Dry electrodes 112 and othersensors are integrated into the insides of these hats to permit formeasurement of electrophysiological signals, including EOG, ECG, and EEGfrom the head. Any tight-fitting headpiece, including a running dew rag,can similarly be used to implement the invention. FIG. 12 shows aheadband or sweatband 121 with dry electrodes 122 incorporated. As inthe other embodiments described, the surface features of the electrodesare advantageous in providing good electrical contact with the skin evenwhen hair is present.

FIGS. 13 and 14 illustrate methods of the present invention in flowchart form. In some embodiments, the method consists of a step 131 ofproviding a device, such as the earbuds/headphones, eyewear or headgearpreviously described, comprising at least one physiological sensor ofthe types previously described. Alternately or in addition, the methodconsists of a step 132 of providing a device comprising secondary orenvironmental sensor(s), i.e., sensors that do not directly measure aphysiological parameter. The data collected from these sensors can beprocessed or used in a variety of ways. Typically, physiological data iscollected and processed in a series of steps. In one step 133,physiological signal(s) is/are measured from the subject using sensor(s)of the device—including ECG, body temperature, SpO₂, GSR, or any of theother listed physiological sensors. In another step 134, the acquireddata is pre-processed, either using hardware circuitry or software knownin the art to be useful to amplify the signal(s) and detect and removeartifacts from the signal(s). Next 135, the pre-processed signal(s)is/are processed, using an algorithm running on a processor, toquantify, analyze, and present the data. For example, ECG waveforms areanalyzed for peaks and interpeak distances.

An optional step 136 of calculating or deriving, using an algorithmrunning on a processor, numerous other metrics from the measuredphysiological signal(s) and/or from the secondary/environmentalsensor(s). These metrics can include heart rate (as by averaginginterpeak distances from an ECG waveform), heart rate variability,stress, sleep cycle, alertness, preparedness, focus, calorimetry,metabolic rate/output, etc. After or before such metrics are calculated,estimated or predicted, any number of steps 137 may be performed. Themeasured and/or derived signals (if any) may be output to a displaydevice 137 a. The signals may be used to actuate one or more of thestimulators 137 e or other actuators 137 b discussed earlier in thisapplication, such actuators being incorporated into the data acquisitioneyewear/headgear/earphones or into a nearby device in communication withthe data acquisition device. This actuation may involve various controlalgorithms that may analyze for feedback the subsequent measured orderived signals, to check for efficacy of the actuation and increase,decrease or alter stimulus as needed. The measured or derived datasignals may be fused with data signals from other sensors to provideuseful feedback and/or recommendations to the user 137 c. An alert orwarning can be provided to the subject 137 d that a physiological orderived signal is at a dangerous level and/or exceeds a high or lowthreshold, etc. Finally, the device can harvest energy from the body orthe environment 137, e.g., from kinetic or solar energy, using knownmethods as described above.

In FIG. 14, signals are acquired from physiological and/orsecondary/environmental sensors 140. These signals are then (a)pre-processed (with filtering, artifact detection, and artifact removal)141 a; (b) outputted and/or stored 141 b; and (c) processed withbiological signal processing 141 c, using methods including waveletanalysis, FFT analysis, etc. Alternatively or additionally, theoriginally acquired signals are analyzed with spectrum analysis todetect and provide an artifact-free ECG signal, either with or withoutpreprocessing 142. In either case, derivation algorithms process themeasured signals to provide calculated, derived, estimated, predicted,or otherwise produced measurements, values or analysis from the measuredsignals 143. Data from sensors is fused 144, and data/signals are thenoutput to display and/or storage device 145, or entered into controlalgorithm to control actuators or provide feedback, alerts, or messagesto the subject 146.

As already described in this disclosure, in various embodiments,preferably, the device or system of the present invention derivesmetrics indicative of one or more of heart rate, heart rate variability,respiration rate, stress, sleep cycle, alertness, concentration, focus,preparedness, calorimetry, or metabolism using one or more of dryelectrodes, body temperature sensors, ambient temperature sensors,galvanic skin response sensors, pulse oximetry sensors, near infraredsensors, GPS sensors, accelerometers, gyroscopes, altimeters, pressuresensors, proximity sensors, audio sensors, video sensors, eye trackingsensors, time sensors, data input by the subject, or data sourced froman external database or the Internet, and subsequently supplies asignal, notification, warning, enticement, encouragement, comfortchange, plan, or program to the subject using one or more ofsoundspeakers, video screens, computer interfaces, user interfaces,haptics actuators, shock stimulators, light emitters, temperatureactuators, or ear pressure equalizers.

It will be apparent to those skilled in the art that variousmodifications and variations can be made to the present inventionwithout departing from the spirit and scope of the invention. Thus, itis intended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

FIG. 15A shows a dry electrode 1500 of the present invention coated witha conductive or ionic compound or material (not shown) from a bottomview, thus depicting the lower surface 1501 of the device, with an arrayof surface features 1502 arranged about the center of the lower surface1501 of the electrode 1500. The surface features 1502 are designed todisplace, crack, or perturb the skin when placed in contact with asubject to allow the device to transmit physiological signals from theconductive layers of the epidermis through the electrode 1500. FIG. 15Bshows the same dry electrode 1500 from FIG. 15A, but from a top view,thus depicting the upper surface 1503 of the device. On top of the dryelectrode 1500 is a connector 1508, in this particular depiction a snapconnector, for electrically and mechanically connecting the dryelectrode 1500 to monitoring equipment (not shown) that may use the dryelectrode 1500 for measuring biopotentials or physiological signals froma subject to whom the dry electrode 100 is attached or applied. FIG. 15Cillustrates a cross section of the dry electrode 1500. Again, theconnector 1508 is located on the upper surface 1503 of the dry electrode1500, and surface features 1502 are located on the lower surface 1501 ofthe monolithic device. Surrounding the base, and constituting the outeredge of the dry electrode, and particularly the lower surface 1501(though the upper surface 1503 may be curved as well) is anencouragement lip 1510 for helping the dry electrode 1500 remain instable, secure contact with a subject's skin by stabilizing and helpingto situate or force the surface features of the dry electrode 1500against the subject's skin. The cross section in FIG. 15C also shows aconductive coating and/or ionic compound 104 (depicted as the hatchedarea surrounding the entire dry electrode), for example of silver/silverchloride (Ag/AgCl), around the entirety of the dry electrode 1500. Theconductive coating and/or ionic compound 1504 facilitates areduction-oxygenation (redox) reaction with ions within a subject'sbiological fluid necessary for recording biopotentials, and furtherhelps minimize electrical impedance and provide a conductive electricalpathway for biopotentials to be transmitted from the lower layers of thepatient's skin (not shown) to the monitoring equipment (not shown).

We claim:
 1. A method of collecting electrocardiogram (ECG) signals of asubject having skin comprising steps of: placing on the subject's headan eyewear apparatus adapted for acquiring physiological signalscomprising eyeglasses frames having temple stems and having a pluralityof dry electrodes along the stems, the dry electrodes each comprising anupper surface and a lower surface, the upper surface comprising a singleconnector and the lower surface comprising a plurality of protrudingsurface features having an aspect ratio of less than 1.5 and beingadapted to in part increase surface area of each electrode contactingthe subject's skin for acquiring physiological signals from the subjectwith a single electrical pathway from the lower surface and itsplurality of surface features to the connector, the eyewear apparatusfurther comprising at least one electronic component; measuringelectrophysiological signals using the dry electrodes to obtain ECGsignals and preparedness data related to the subject's physical abilityto complete a defined physical task or activity during which themeasurement is performed; amplifying and filtering theelectrophysiological signals with the at least one electronic componentto produce ECG signals; determining a preparedness of the subject toperform the defined physical task or activity by comparing a second setof measured electrophysiological signals and preparedness data to storedelectrophysiological signals and preparedness data related to thesubject's physical ability to complete the physical task or activity orsuch data for other subjects; and storing the ECG signals, preparednessdata, and/or the preparedness determination with the at least oneelectronic component for collection or processing, or transmitting theECG signals, preparedness data, and/or preparedness determination withthe at least one electronic component to an additional electroniccomponent for storage, collection or processing.
 2. The method of claim1, further comprising the step of providing an advanced assisted heartrate program based at least in part on measuring the subject's restingheart rate, lactate threshold heart rate, and maximum heart rate tomeasure or estimate the subject's heart rate response to the definedphysical task or activity.
 3. The method of claim 2, wherein electroniccomponents of the eyewear apparatus are powered by a rechargeablebattery and the method further includes the step of recharging thebattery using energy harvesting photovoltaic, piezoelectric, and/orbiomechanical or kinetic elements.
 4. The method of claim 1, furthercomprising a step of determining and providing a training regimendirected to improving the subject's preparedness for the defined task oractivity by improving the measured preparedness data of the subject. 5.The method of claim 4, wherein the eyewear apparatus further comprisesat least one haptic actuator adapted to provide tactile feedback to thesubject based on physiological signals from the dry electrodes, datarelated to the physiological signals from the dry electrodes, and/ormeasured, calculated, or derived metrics.
 6. The method of claim 4,further comprising a step of calculating a metabolic rate and/orcalories burned during a physical activity for the subject based atleast in part on personal information about the subject and at least inpart on the ECG signals obtained and produced by the eyewear apparatusand/or the preparedness data related to the subject's physical abilityto complete the defined physical task or activity.
 7. The method ofclaim 6, wherein the eyewear apparatus further comprises a heads-updisplay (HUD) adapted to display data and messages to the subjectcorresponding to physiological signals from the dry electrodes, datarelated to the physiological signals from the dry electrodes, and/ormeasured, calculated, or derived metrics.
 8. A method of collectingelectrocardiogram (ECG) signals of a subject having skin comprisingsteps of: placing on the subject's head an eyewear apparatus adapted foracquiring physiological signals comprising eyeglasses frames havingtemple stems and having a plurality of dry electrodes along the stems,the dry electrodes each comprising an upper surface and a lower surface,the upper surface comprising a single connector and the lower surfacecomprising a plurality of protruding surface features having an aspectratio of less than 1.5 and being adapted to in part increase surfacearea of each electrode contacting the subject's skin for acquiringphysiological signals from the subject with a single electrical pathwayfrom the lower surface and its plurality of surface features to theconnector, the eyewear apparatus further comprising at least oneelectronic component and a heads-up display (HUD) adapted to displaydata and messages to the subject corresponding to physiological signalsfrom the dry electrodes, data related to the physiological signals fromthe dry electrodes, and/or measured, calculated, or derived metrics;measuring electrophysiological signals using the dry electrodes toobtain ECG signals and preparedness data related to the subject'sphysical ability to complete a defined physical task or activity duringwhich the measurement is performed; amplifying and filtering theelectrophysiological signals with the at least one electronic componentto produce ECG signals; determining a preparedness of the subject toperform the defined physical task or activity by comparing a second setof measured electrophysiological signals and preparedness data to storedelectrophysiological signals and preparedness data related to thesubject's physical ability to complete the physical task or activity orsuch data for other subjects; and storing the ECG signals, preparednessdata, and/or the preparedness determination with the at least oneelectronic component for collection or processing, or transmitting theECG signals, preparedness data, and/or preparedness determination withthe at least one electronic component to an additional electroniccomponent for storage, collection or processing.
 9. The method of claim8, further comprising the step of providing an advanced assisted heartrate program based at least in part on measuring the subject's restingheart rate, lactate threshold heart rate, and maximum heart rate tomeasure or estimate the subject's heart rate response to the definedphysical task or activity.
 10. The method of claim 9, wherein electroniccomponents of the eyewear apparatus are powered by a rechargeablebattery and the method further includes the step of recharging thebattery using energy harvesting photovoltaic, piezoelectric, and/orbiomechanical or kinetic elements.
 11. The method of claim 8, furthercomprising a step of calculating a metabolic rate and/or calories burnedduring a physical activity for the subject based at least in part onpersonal information about the subject and at least in part on the ECGsignals obtained and produced by the eyewear apparatus and/or thepreparedness data related to the subject's physical ability to completethe defined physical task or activity.
 12. The method of claim 8,further comprising a step of determining and providing a trainingregimen directed to improving the subject's preparedness for the definedtask or activity by improving the measured preparedness data of thesubject.
 13. The method of claim 12, wherein the eyewear apparatusfurther comprises at least one haptic actuator adapted to providetactile feedback to the subject based on physiological signals from thedry electrodes, data related to the physiological signals from the dryelectrodes, and/or measured, calculated, or derived metrics.
 14. Amethod of collecting electrocardiogram (ECG) signals of a subject havingskin comprising steps of: placing on the subject's head an eyewearapparatus adapted for acquiring physiological signals comprisingeyeglasses frames having temple stems and having a plurality of at leastfour dry electrodes along the stems, the dry electrodes each comprisingan upper surface and a lower surface, the upper surface comprising asingle connector and the lower surface comprising a plurality ofprotruding surface features having an aspect ratio of less than 1.5 andbeing adapted to in part increase surface area of each electrodecontacting the subject's skin for acquiring physiological signals fromthe subject with a single electrical pathway from the lower surface andits plurality of surface features to the connector, the eyewearapparatus further comprising at least one electronic component and atleast one haptic actuator adapted to provide tactile feedback to thesubject physiological signals from the dry electrodes, data related tothe physiological signals from the dry electrodes, and/or measured,calculated, or derived metrics; measuring electrophysiological signalsusing the dry electrodes to obtain ECG signals and preparedness datarelated to the subject's physical ability to complete a defined physicaltask or activity during which the measurement is performed; amplifyingand filtering the electrophysiological signals with the at least oneelectronic component to produce ECG signals; determining a preparednessof the subject to perform the defined physical task or activity bycomparing a second set of measured electrophysiological signals andpreparedness data to stored electrophysiological signals andpreparedness data related to the subject's physical ability to completethe physical task or activity or such data for other subjects; andstoring the ECG signals, preparedness data, and/or the preparednessdetermination with the at least one electronic component for collectionor processing, or transmitting the ECG signals, preparedness data,and/or the preparedness determination with the at least one electroniccomponent to an additional electronic component for storage, collectionor processing.
 15. The method of claim 14, wherein the eyewear apparatusfurther comprises a heads-up display (HUD) adapted to display data andmessages to the subject corresponding to physiological signals from thedry electrodes, data related to the physiological signals from the dryelectrodes, and/or measured, calculated, or derived metrics.
 16. Themethod of claim 14, further comprising a step of calculating a metabolicrate and/or calories burned during a physical activity for the subjectbased at least in part on personal information about the subject and atleast in part on the ECG signals obtained and produced by the eyewearapparatus and/or the preparedness data related to the subject's physicalability to complete the defined physical task or activity.
 17. Themethod of claim 14, further comprising the step of providing an advancedassisted heart rate program based at least in part on measuring thesubject's resting heart rate, lactate threshold heart rate, and maximumheart rate to measure or estimate the subject's heart rate response tothe defined physical task or activity.
 18. The method of claim 17,wherein electronic components of the eyewear apparatus are powered by arechargeable battery and the method further includes the step ofrecharging the battery using energy harvesting photovoltaic,piezoelectric, and/or biomechanical or kinetic elements.
 19. The methodof claim 14, further comprising a step of determining and providing atraining regimen directed to improving the subject's preparedness forthe defined task or activity by improving the measured preparedness dataof the subject.
 20. The method of claim 19, wherein symptom or subjectexperience data is provided and the method further comprises a step ofdevising or proposing at least one test or experiment for the subject toundertake during which one or more variables are measured and adiagnostic determination is made for a cause of a the provided symptomor a condition related to the symptom or subject experience data of thesubject based on the one or more measured variables.